Agents for treatment of HCV and methods of use

ABSTRACT

An amphipathic helix at the approximate N-terminus of Hepatitis C virus (HCV) nonstructural proteins mediates the association of these proteins with cytoplasmic membranes in infected cells. This association is essential for replication. Thus, assessing the ability of compounds or protocols to disrupt the association of such helices with cytoplasmic membranes permits identification of compounds and protocols which are useful in the treatment of HCV infection. Also useful in the invention are mimics, or function-disrupting ligands, of an amphipathic helix of the nonstructural proteins described herein and antibodies and fragments thereof immunoreactive with said helix.

This application is a divisional of U.S. patent application Ser. No. 11/899,393, filed Sep. 4, 2007, now U.S. Pat. No. 8,093,353, which is a continuation of U.S. patent application Ser. No. 10/481,261, filed Jul. 30, 2004, now U.S. Pat. No. 7,326,536, which is a national stage filing under 35 U.S.C. §371 of International Patent Application No. PCT/US2002/13951, filed May 3, 2002, which claims priority to U.S. Provisional Patent Application No. 60/288,687, filed May 3, 2001, and claims priority to U.S. Provisional Patent Application No. 60/316,805, filed Aug. 31, 2001, each of which applications is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The invention relates generally to Hepatitis C virus (HCV) infection, and more specifically to interrupting the mechanism of infection by HCV and to methods to identify agents, which effect this interruption. The invention also relates to interfering with the ability of HCV components to bind with cellular membranes of an infected cell.

BACKGROUND

Hepatitis C virus (HCV) establishes a chronic infection in a high percentage of infected individuals and is associated with progressive liver pathology, including cirrhosis and hepatocellular carcinoma. Antiviral drugs such as interferon alpha and ribavirin have had limited success in controlling HCV infection. As a result, it has become the leading cause for liver transplantation in the US. The HCV polyprotein comprises, from the amino terminus to the carboxy terminus, the core protein (C), the envelope proteins (E1 and E2), p7, a membrane bound protein, whose function is unknown and the non-structural proteins (NS2, NS3, NS4A, NS4B, NS5A and NS5B) which are believed to be important for replication. C codes for the core nucleocapsid protein, E1 and E2 are envelope proteins that coat the virus, NS2, NS3 and NS4A are involved in proteolytic processing of the HCV polyprotein, and NS5B has RNA polymerase activity. The functions of NS4B and NS5A are unknown.

Hepatitis C virus is a significant cause of morbidity and mortality, infecting over 100,000,000 people worldwide. Annual HCV related costs in the United States are about $1 billion. Current therapies are clearly inadequate; the best available treatment at present is the combination of interferon and ribavirin, a treatment which is inconveniently lengthy as it typically lasts over one and a half years, difficult to tolerate in that most patients have flu-like symptoms, and extremely expensive as the cost is in the range of thousands of dollars annually. Not only does the present treatment have these disadvantages, but it is also not particularly effective.

Certain interactions of viral proteins with cell membranes have previously been described. For example, in poliovirus and Hepatitis A virus, the nonstructural protein 2C contains a membrane associating amphipathic helix (See Teterina, N. L., et al., J. Virol. (1997) 71:8962-8972 (poliovirus); and Kusov, Y. Y., et al., Arch. Virol. (1998) 143:931-944 (Hepatitis A). This membrane association appears to play a role in RNA synthesis in poliovirus (Paul, A. V., et al., Virol. (1994) 199:188-199). Replication complexes are localized on the host endoplasmic reticulum (ER) and Golgi in the case of poliovirus (Bienz, K., et al., J. Virol. (1992) 66:2740-2747), and infection with poliovirus induces rearrangements of membranes derived from host ER and Golgi (Schlegel, A., et al., J. Virol. (1996) 70:6576-6588).

It is also known that the Hepatitis C nonstructural 5A protein illustrated below is a potent transcriptional activator (Kato, N., et al., J. Virol. (1997) 71:8856-8859); that amino terminal deletion mutants of Hepatitis C virus nonstructural protein NS5A function as transcriptional activators in yeast (Tanimoto, A., et al., Biochem. Biophys. Res. Commun. (1997) 236:360-364); and that this nonstructural protein physically associates with p53 and regulates p21/Waf1 gene expression in a p53 dependent manner (Majumder, M., et al., J. Virol. (2001) 75:1401-1407).

It has also been reported that a number of positive strand RNA viruses, like HCV, replicate in association with cytoplasmic membranes, although the precise manner of such association and replication is not understood. See, for example, Lazarus, L. H., et al., J. Gen. Virol. (1974) 23:213-218 (foot and mouth disease); Bienz, K., et al., Virol. (1980) 100:390-399 (polio); Froshauer, S., et al., J. Cell. Biol. (1988) 107:2075-2086 (alphavirus); Chu, P. W., et al., Arch. Virol. (1992) 125:177-191 (Kunjin virus); Rice, C. M., in Fields Virology, Fields, B. N., et al., Ed. (1996) Lippincott-Raven Publications: Philadelphia, Pa., pages 931-959 (Flaviviridae).

It is also known that NS5A, the nonstructural Hepatitis C protein used for illustration below is associated with cell membranes (Selby, M. J., et al., J. Gen. Virol. (1993) 74:1103-1113; Hijikata, M., et al., Proc. Natl. Acad. Sci. USA (1993) 90:10773-10777; Moradpour, D., et al., Hepatol. (1998) 28:192-201). This protein, NS5A, also has been reported to interact with other host cell proteins such as PKR protein kinase (Gale, M. J. J., et al., Virol. (1997) 290:217-227) and a SNARE-like protein (Tu, H., et al., Virol. (1999) 263:30-41). NS5A has also been implicated in determining the response to interferon therapy in some groups of patients (Gale, M. J. J., et al., Virol., supra); Enomoto, H., et al., N. Engl. J. Med. (1996) 334:77-81.

There exists a need in the art for compositions, including peptide therapeutics, and methods employing the same, to prevent or inhibit infections due to Hepatitis C Virus, including inhibiting replication and/or pathogenesis due to HCV, with minimal or no adverse side effects.

SUMMARY OF THE INVENTION

The present invention is based on the discovery that the presence of an amphipathic helix located near the N-terminus of certain nonstructural proteins of HCV is required to associate these proteins with the cellular membranes in the infected host. Three such HCV nonstructural proteins, NS4B, NS5A and NS5B are known to be associated with the host cellular membranes and thus participate in the replication of HCV, which is considered to occur in association with cytoplasmic membranes and thus are implicated in the participation of replication of HCV. These proteins contain at least one amphipathic helix of about 20-25 amino acids in the N-terminal region which, when disrupted, can result in failure of these proteins to properly associate with cellular membranes. The ability of candidate reagents to interfere with this binding can readily be assessed by linking the amphipathic helix to a label, such as a reporter protein, and assessing the effects of candidate agents on the position of the reporter in the cell. Such an assay can be conducted in cell culture, and thus can overcome one significant obstacle to discovery of additional treatments for Hepatitis C viral infection.

There is a plethora of alternative methods other than this straightforward approach to assess the ability of a candidate substance or protocol to disrupt the necessary binding between the relevant amphipathic helix and the cytoplasmic cellular membranes. These approaches will be described in greater detail below.

Thus, in one aspect, the invention is directed to a method to identify a compound or protocol which is useful in treating HCV infection, which method comprises assessing the ability of a candidate compound or protocol to disrupt the binding of a peptide comprising an amphipathic helix derived from a Hepatitis C nonstructural protein, in particular NS4B, NS5A or NS5B, to cellular membranes.

This can be done, for example, by simply assessing the binding of a candidate compound to said peptide, wherein a compound which binds said peptide is identified as an anti-HCV agent. Alternatively, the ability of a candidate compound to inhibit the binding of a peptide containing the amphipathic helix to a membrane preparation from eukaryotic cells can be evaluated. In these aspects, the assay can be carried out using straightforward laboratory procedures, not even involving cell culture.

Another alternative method to identify compounds that are effective anti-HCV agents comprises providing cells which contain an amphipathic helix derived from Hepatitis C viral nonstructural proteins NS4B, NS5A or NS5B coupled to a detectable label; treating one sample of said cells with the candidate compound or protocol and maintaining a sample of said cells in the absence of said candidate compound or protocol; comparing the location of the label in cells treated with said compound or protocol as compared to cells not treated with said compound or protocol, whereby when cells in the presence of the candidate compound or protocol show a different cellular distribution of label as compared to cells not treated with said compound or protocol, said compound or protocol is identified as an agent or protocol for treating HCV.

Alternatively, a compound or protocol can be identified as an anti-HCV agent by linking the amphipathic helix derived from the N-terminal region of certain HCV nonstructural proteins and a reporter or label and observing the behavior of the reporter intracellularly. This can be done directly as described above by observing the intracellular location of a reporter that is a simple label or can take advantage of secondary effects of the reporter. For example, as described below, disrupting the binding of the nonstructural protein NS5A with the cytoplasmic membrane by disrupting the amphipathic helix results in translocation of the nonstructural protein to the nucleus. Thus, if the reporter includes a nuclear localization signal, the disruption of interaction with the cytoplasmic membrane can be measured indirectly by assessing the effects of translocation of the helix and its reporter functions to the nucleus as will be described in further detail below.

In another aspect, the invention is directed to methods of treating HCV by administering to a subject in need of such treatment an agent or protocol identified by the methods described above or by an agent or protocol which disrupts the interaction of an amphipathic helix derived from HCV nonstructural proteins with cellular membranes or with an agent that binds to said helix. The invention is also directed to agents and protocols identified by the method of the invention. The nature of some of the agents and protocols which will disrupt the binding of these helices to cellular membranes is apparent without the necessity for carrying out the above-described assays. For example, one approach is to employ the amphipathic helix itself as a competitor for the helix as it exists in the infective agent. Thus, peptides having the amino acid sequence corresponding to the sequence in the helices of the various HCV nonstructural proteins can be used as pharmaceuticals to compete with the helices contained in the nonstructural proteins themselves. In addition, molecules which mimic the pattern of hydrophilic or hydrophobic faces of the helix can be employed. Peptides which contain non-amide bonds but which retain the same essential backbone shape could also be used, as could aptamers which assemble to obtain the essential features of the helix. It may be possible by ascertaining the three-dimensional structure of the helix, the appropriate antibodies, or aptamers to design rationally organic molecules that assume the same charge/spatial configuration. Thus, the invention also includes these embodiments.

In another aspect, the invention is directed to a peptide of not more than about 60 amino acid residues, which is an HCV nonstructural protein amphipathic helix, where the peptide optionally contains non-peptide isosteric linkages, and where the peptide is optionally coupled to an additional heterologous second peptide or to an additional component.

In yet another aspect, the invention provides an isolated peptide that interferes with the binding of an amphipathic helix derived from HCV nonstructural proteins with cellular membranes.

In still another aspect, the invention provides a peptide that inhibits the association of an amphipathic helix present in the N-terminus of an HCV nonstructural protein with cytoplasmic membranes of a cell and having an amino acid sequence SGSWLRDVWDWICTVLTDFKTWLQSKL (SEQ ID NO: 14), and variants and mutants thereof, and wherein the peptide is identified by assessing the ability of the peptide to interfere with the binding of an amphipathic helix present in the N-terminus of an HCV nonstructural protein with cytoplasmic membranes of a eukaryotic cell, where a peptide which interferes with binding is identified as useful in treating HCV infection.

In yet another aspect, the invention provides a method of screening for a peptide useful as an inhibitor of the binding of an HCV nonstructural protein with cytoplasmic membranes of a eukaryotic cell by contacting an amphipathic helix present in the N-terminus of an HCV nonstructural protein with cytoplasmic membranes of a eukaryotic cell, both in the presence and absence of a test compound, wherein a decreased level of binding in the presence of the compound as compared to the level in the absence is indicative of a peptide inhibitor.

In another embodiment, the invention provides an isolated peptide selected from complementary peptides or competitive inhibitors, functional fragments, mutants or variants thereof, wherein the isolated peptide causes inhibition of infection, replication, or pathogenesis of Hepatitis C Virus in vitro or in vivo when introduced into a host cell containing said virus, and wherein said isolated peptide exhibits an IC₅₀ in the range of from about 0.0001 nM to about 100 μM in an in vitro assay for at least one step in infection, replication, or pathogenesis of said virus.

In yet another embodiment, the invention provides a composition of one or more isolated peptides of the invention, functional fragments, mutants or variants thereof, and a carrier, a diluent, an excipient or a buffer.

In still another embodiment, the invention provides a pharmaceutical composition of one or more isolated peptides of the invention, functional fragments, mutants or variants thereof, and a pharmaceutically acceptable carrier, diluent, excipient, or buffer.

In another embodiment, the invention provides a method of preventing or treating HCV infection in a patient in need thereof, comprising administering to said patient an anti-HCV effective amount of an isolated peptide of the invention, functional fragments, mutants or variants thereof.

In another embodiment, the invention provides use of an isolated peptide selected from the peptide of the invention, functional fragments, mutants or variants thereof in the preparation of a medicament for the prevention or treatment of HCV infection in a human patient in need thereof.

In yet another embodiment, the invention provides a method of treatment of HCV infection in a patient in need thereof, comprising administering to said patient an anti-HCV effective amount of an isolated peptide of the invention, comprising the NS5A amphipathic helix or a functional fragment thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows amino acid sequences (SEQ ID NOS: 1-13) which comprise amphipathic helices in the N-terminal region of NS4B, NS5A and NS5B of Hepatitis C virus genotype 1a. Helices of NS5A from a variety of isolates are particularly exemplified.

FIGS. 2A-2J show the helical conformation of sequences in the various isolates of NS5A (SEQ ID NOS: 469 and 5-13, respectively).

FIGS. 3A-3C, lower panels, show the conformation of amino acid sequences in positions 4-27 of NS5A which form the N-terminal helix in the native protein (FIG. 3A; SEQ ID NO: 297) but wherein the helical structure is deleted (FIG. 3B; SEQ ID NO: 297) or wherein the hydrophobic region is interrupted (FIG. 3C; SEQ ID NO: 470).

FIGS. 3A-3C, upper two panels, show the effect of the alterations to the helical structure on the cellular distribution pattern of NS5A. FIG. 3A shows the pattern obtained when the helix is not disrupted; FIGS. 3B and 3C show the patterns obtained when the helix is deleted or the hydrophobic face is disrupted.

FIGS. 4A-4C show the distribution patterns of the N-terminal amphipathic helix of NS5A coupled to green fluorescent protein (GFP) in comparison to suitable controls. FIG. 4B shows the localization pattern of the fusion protein of the helix with GFP; FIG. 4A shows the pattern for GFP alone, and FIG. 4C shows the pattern obtained when the hydrophobic face of the helix is disrupted.

FIGS. 5A and 5B, upper panels, show schematics of subgenomic replicons of HCV used in HCV replication assays; FIGS. 5A and 5B, lower panels, show the results of these assays.

FIGS. 6A-6C show the results of a membrane floatation assay for binding of the NS5A amphipathic helix with microsomal membrane.

FIGS. 7A and 7B show the effects of a peptide useful as an anti-HCV agent on binding of NS5A to the microsomal membrane using a floatation assay.

FIG. 8 shows pharmacologic inhibition of NS5A membrane association.

DETAILED DESCRIPTION OF THE INVENTION

The Hepatitis C virus has been well studied and the genome has been completely sequenced. The genome of HCV is a single-stranded RNA of 9.6 kb that encodes a single approximately 3,010 amino acid polyprotein. This polyprotein is proteolytically processed into structural proteins and nonstructural proteins. HCV, like other positive strand RNA viruses, is thought to replicate in association with cytoplasmic membranes; and the approximately 447 amino acid nonstructural protein, NS5A is known to associate with host cell membranes. This protein is thus believed to play a key role in replication. The discovery of alternative treatments has been hampered by the lack of a cell culture model for HCV. The present invention overcomes this problem, and provides a convenient assay for identifying agents that can directly and specifically curtail the course of HCV infection. As noted above, the present invention resides in the discovery of a mechanism to disrupt association between certain nonstructural proteins of the virus and cytoplasmic membranes.

Administration of peptides and proteins intracellularly has been limited by the lack of consistent and efficient uptake across the cell membrane. However, various membrane translocation sequences (MTS) have been identified which allow the transduction of peptides across the plasma membrane (for example, References 10, 13, 14, 16, 17, 20, 21 and 22). While unknown, it is hypothesized that the mechanism of the transduction is that an MTS is able to transport both peptides and full-length proteins into the cytoplasm of cells. It is believed that the separate peptides form a noncovalent complex in solution that is then transported into the cell.

It has now been found that an amphipathic helix consisting of about 20-25 amino acids is critical to the association of NS5A with cytoplasmic membranes, for example endoplasmic reticulum (ER), as are similar helices found in NS4B and NS5B. As shown below, when the amphipathic nature of the helix is disrupted, NS5A no longer associates with cell membranes; in addition, the helix when coupled to other substances, including other proteins, effects association of the carried component to the cell's cytoplasmic membranes. As used herein, “cytoplasmic membrane” refers to a structure contained in the cellular cytoplasm, which can generally be recognized as a membrane structure for example, membranes of the endoplasmic reticulum (ER). The membranes may include protein receptors or other elements in addition to the more hydrophobic portions of the membrane per se which may account at least in part for the association of the amphipathic helix to the “cytoplasmic membrane”. No theory is advanced as to the mechanism whereby the amphipathic helix associates itself with the cytoplasmic membrane, and thus the precise elements contained in the membrane, which are responsible for this association, are not defined. The observations related to the screening methods described below are not dependent on any definition: intracellular embodiments of these assays rely on direct observation of the cellular distribution of the helix and its label and studies which involve membrane preparations ex vivo employ compositions of cytoplasmic membranes as conventionally prepared, without regard to substructure. This amphipathic helix feature is found in nonstructural proteins of isolates of many strains of HCV of various geographical origins. It is also demonstrated below that disruption of the amphipathic nature of the helix of NS5A prevents replication of HCV RNA.

FIG. 1 shows the amino acid sequences of the amphipathic helices that have been found near to the N-terminus of three nonstructural proteins from prototype genotype 1a representing amino acids 7-34 of NS4B (SEQ ID NO: 1), amino acids 5-26 of NS5A (SEQ ID NO: 2), and two amphipathic helical regions of NS5B, amino acids 65-87 (SEQ ID NO: 3) and 107-125 (SEQ ID NO: 4). This figure also shows the relevant sequences in NS5A for additional genotypes 1b (acc. No. P26663) (SEQ ID NO: 5); 2a (acc. No. P26660) (SEQ ID NO: 6); 2b (acc. No. AB030907) (SEQ ID NO: 7); 3a-K (acc. No. D28917) (SEQ ID NO: 8); 3a-NZL (acc. No. D17763) (SEQ ID NO: 9); 3b (acc. No. D49374) (SEQ ID NO: 10); 4a (acc. No. Y11604) (SEQ ID NO: 11); 10a (acc. No. D63821) (SEQ ID NO: 12); and 11a (acc. No. D63822) (SEQ ID NO: 13). The sequences listed in FIG. 1 are not an exhaustive list of the amino acid sequences of amphipathic helices of these three nonstructural proteins. NS4B and NS5B may be expanded similarly to NS4A in FIG. 1. Although the sequences per se are not completely homologous, they are all capable of forming amphipathic helices. (See FIGS. 2A-2J which show these helices from the NS5A proteins.) Thus, it is clear that the presence of the N-terminal amphipathic helix, containing a sequence of approximately 20-25 amino acids is widespread in the nonstructural proteins of HCV and in various isolates.

As used herein, the term “HCV nonstructural protein amphipathic helix” refers to a sequence of at least 15 amino acids, preferably at least 20 amino acids and preferably not more than 30, more preferably not more than 25 amino acids which has the amino acid sequence selected from the group consisting of those set forth in FIG. 1, or which is at least 80% homologous, preferably at least 90% homologous and more preferably at least 95% homologous to at least one of said sequences and which retains the ability to form an amphipathic helix. While it is known that certain amino acid substitutions will result in peptides, which, while they retain the required degree of homology (sequence identity), will disrupt the formation of the helix, the nature of these substitutions is already understood by those of ordinary skill and can be avoided, or purposefully used, as desired. Insertion of, for example, disruptive proline residues, is understood to be undesirable. Thus, it is well within ordinary skill to substitute one or more amino acids in these sequences to obtain substitute helices with the required degree or homology, avoiding unsuccessful substitutions.

It should be noted that in certain embodiments of the invention, the amphipathic helix may be other than a peptide; for example, it may constitute a pseudopeptide where the native peptide linkages are substituted by isosteres as is understood in the art. Similarly, alternative polymeric structures can be designed which mimic the charge and shape distribution of these amphipathic helices and mutants and variants thereof. These homologs and analogs are included within the scope of the invention and are useful both in therapeutic protocols and in assay systems for ascertaining alternative compounds and protocols which will be useful in treating HCV infection.

As used herein, the term “amino acid” is applicable not only to cell membrane-permeant peptides, but also to amphipathic helices and anti-HCV peptides useful as pharmaceutical agents, i.e., all the individual components of the present compositions.

The term “amino acid” is used herein in its broadest sense, and includes naturally occurring amino acids as well as non-naturally occurring amino acids, including amino acid analogs and derivatives. The latter includes molecules containing an amino acid moiety. One skilled in the art will recognize, in view of this broad definition, that reference herein to an amino acid includes, for example, naturally occurring protogenic L-amino acids; D-amino acids; chemically modified amino acids such as amino acid analogs and derivatives; naturally occurring non-protogenic amino acids such as norleucine, β-alanine, ornithine, etc.; and chemically synthesized compounds having properties known in the art to be characteristic of amino acids. As used herein, the term “protogenic” indicates that the amino acid can be incorporated into a peptide, polypeptide, or protein in a cell through a metabolic pathway.

The incorporation of non-natural amino acids, including synthetic non-native amino acids, substituted amino acids, or one or more D-amino acids into the present anti-HCV peptides of the present invention is advantageous in a number of different ways. D-amino acid-containing peptides exhibit increased stability in vitro or in vivo compared to L-amino acid-containing counterparts. Thus, the construction of peptides incorporating D-amino acids can be particularly useful when greater intracellular stability is desired or required. More specifically, D-peptides, etc., are resistant to endogenous peptidases and proteases, thereby providing improved bioavailability of the molecule, and prolonged lifetimes in vivo when such properties are desirable. When it is desirable to allow the peptide, etc., to remain active for only a short period of time, the use of L-amino acids therein will permit endogenous peptidases, proteases, etc., in a cell to digest the molecule in vivo, thereby limiting the cell's exposure to the molecule. Additionally, D-peptides, etc., cannot be processed efficiently for major histocompatibility complex class II-restricted presentation to T helper cells, and are therefore less likely to induce humoral immune responses in the whole organism.

One factor that can be considered in making such changes is the hydropathic index of amino acids. The importance of the hydropathic amino acid index in conferring interactive biological function on a protein has been discussed by Kyte and Doolittle (1982, J. Mol. Biol., 157: 105-132). It is accepted that the relative hydropathic character of amino acids contributes to the secondary structure of the resultant protein. This, in turn, affects the interaction of the protein with molecules such as enzymes, substrates, receptors, DNA, antibodies, antigens, etc.

Based on its hydrophobicity and charge characteristics, each amino acid has been assigned a hydropathic index as follows: isoleucine (+4.5); valine (+4.2); leucine (+3.8); phenylalanine (+2.8); cysteine/cystine (+2.5); methionine (+1.9); alanine (+1.8); glycine (−0.4); threonine (−0.7); serine (−0.8); tryptophan (−0.9); tyrosine (−1.3); proline (−1.6); histidine (−3.2); glutamate/glutamine/aspartate/asparagine (−3.5); lysine (−3.9); and arginine (−4.5).

As is known in the art, certain amino acids in a peptide, polypeptide, or protein can be substituted for other amino acids having a similar hydropathic index or score and produce a resultant peptide, etc., having similar biological activity, i.e., which still retains biological functionality. In making such changes, it is preferable that amino acids having hydropathic indices within ±2 are substituted for one another. More preferred substitutions are those wherein the amino acids have hydropathic indices within ±1. Most preferred substitutions are those wherein the amino acids have hydropathic indices within ±0.5.

Like amino acids can also be substituted on the basis of hydrophilicity. U.S. Pat. No. 4,554,101, herein incorporated by reference, discloses that the greatest local average hydrophilicity of a protein, as governed by the hydrophilicity of its adjacent amino acids, correlates with a biological property of the protein. The following hydrophilicity values have been assigned to amino acids: arginine/lysine (+3.0); aspartate/glutamate (+3.0±1); serine (+0.3); asparagine/glutamine (+0.2); glycine (0); threonine (−0.4); proline (−0.5±1); alanine/histidine (−0.5); cysteine (−1.0); methionine (−1.3); valine (−1.5); leucine/isoleucine (−1.8); tyrosine (−2.3); phenylalanine (−2.5); and tryptophan (−3.4). Thus, one amino acid in a peptide, polypeptide, or protein can be substituted by another amino acid having a similar hydrophilicity score and still produce a resultant peptide, etc., having similar biological activity, i.e., still retaining correct biological function. In making such changes, amino acids having hydropathic indices within ±2 are preferably substituted for one another, those within ±1 are more preferred, and those within ±0.5 are most preferred.

As outlined above, amino acid substitutions in the anti-HCV peptides of the present invention can be based on the relative similarity of the amino acid side-chain substituents, for example, their hydrophobicity, hydrophilicity, charge, size, etc. Exemplary substitutions that take various of the foregoing characteristics into consideration in order to produce conservative amino acid changes resulting in silent changes within the present peptides, etc., can be selected from other members of the class to which the naturally occurring amino acid belongs. Amino acids can be divided into the following four groups: (1) acidic amino acids; (2) basic amino acids; (3) neutral polar amino acids; and (4) neutral non-polar amino acids. Representative amino acids within these various groups include, but are not limited to: (1) acidic (negatively charged) amino acids such as aspartic acid and glutamic acid; (2) basic (positively charged) amino acids such as arginine, histidine, and lysine; (3) neutral polar amino acids such as glycine, serine, threonine, cysteine, cystine, tyrosine, asparagine, and glutamine; and (4) neutral non-polar amino acids such as alanine, leucine, isoleucine, valine, proline, phenylalanine, tryptophan, and methionine.

It should be noted that changes which are not expected to be advantageous can also be useful if these result in the production of functional sequences. Since small peptides, etc., can be easily produced by conventional solid phase synthetic techniques, the present invention includes peptides, etc., such as those discussed herein, containing the amino acid modifications discussed above, alone or in various combinations. To the extent that such modifications can be made while substantially retaining the activity of the peptide, they are included within the scope of the present invention. The utility of such modified peptides, etc., can be determined without undue experimentation by, for example, the methods described herein.

Based on the present discoveries, various methods to identify agents and protocols which would be effective in treating HCV are made possible. In their simplest form, since binding between the helix and the cytoplasmic membrane is a necessary condition for association of the nonstructural protein with the membrane and is required for the virus to replicate, compounds which simply bind the helix compete with the cellular membranes for this association. When the helix is contained in a substantially larger molecule, such as existing in the context of a significantly longer amino acid sequence, it is possible that the remaining portion of the molecule or amino acid sequence may itself contain elements that are capable of affecting binding. Thus, in the assays of the invention, appropriate controls may be required to ensure that it is the interaction of the helix with the compounds tested or the membranes tested that is being measured. Compounds that bind to the helix would inhibit the required cellular binding, and by identifying compounds that bind with high affinity to the helix compounds that would be successful in interfering with the binding will be found. By “high affinity” is meant binding with a dissociation constant of <10⁻⁴, preferably <10⁻⁶, and more preferably <10⁻⁸. Dissociation constants can be determined using methods generally known in the art; for example the helix could be bound to solid support and labeled compound at varying concentrations supplied wherein the amount of label coupled to solid support can be readily determined.

Alternatively, the peptide comprising the helix can be displayed using standard phage display techniques and the phage tested for ability to bind to compounds that are coupled to solid supports. Phage display is also utilized to screen random peptides to screen for competitive inhibitors of the amphipathic helix. Such peptides would block virus from binding to the receptor.

There are a variety of techniques well known in the art for assessing binding of compounds to targets. A wide variety of detectable labels can be used, and the assays can be conducted in heterogeneous or homogeneous formats. For example, the compound itself can be labeled for detection of its ability to transport label to solid support, to which solid support has been bound the amphipathic helix or, vice versa, the amphipathic helix can be labeled and the compound to be tested can be coupled to solid support. The assay can also be conducted in a homogeneous format using fluorescence techniques, for example, where the fluorescence of a fluorescent label attached to the compound is altered by virtue of its binding to a peptide the size of the amphipathic helix or larger.

The amphipathic helix itself can be supplied in the context of the nonstructural protein or fragment thereof or can be supplied per se or as a fusion protein that contains a label, such as green fluorescent protein.

In a variation of this extracellular format, the effect of individual compounds or mixtures of compounds on the binding of the amphipathic helix or a protein containing it with a membrane preparation can be evaluated. Techniques similar to those described above may be used—e.g., the membrane preparation may be labeled and the amphipathic helix or protein containing it coupled to solid support or displayed using phage. The coupling of the label to solid support containing the helix or relevant protein or to the phage displayed helix in the presence and absence of compound or mixtures of compounds can be determined. These assays can be conducted in homogeneous format by using fluorescence labeling, for example, of the amphipathic helix. A wide variety of such protocols is known in the art, and the essential feature is determination of the effect of the compound or a mixture of compounds on the binding of the amphipathic helix or a protein containing it and the membrane preparation. Perhaps a particularly convenient embodiment of this method would involve a fusion between the amphipathic helix and green fluorescent protein which could be produced very conveniently using recombinant techniques; assessment of the binding of this fusion to the membrane preparation either in a heterogeneous or homogeneous format can then be performed.

As further described below, in Example 3, an assay for binding of the amphipathic helix to the microsomal membrane can be performed by treating a microsomal or cytoplasmic membrane preparation in vitro with a peptide containing the helix and distributing the contents of the reaction mixture in a sedimentation gradient. The helix coupled to membrane will reside in a relatively low density portion of the gradient and is thus separated from mere debris that is found at the bottom of the gradient. The floated helix can be detected in the appropriate gradient fraction using polyacrylamide gel electrophoresis. The helix may be labeled for example, with a radioisotope or a coupled fluorescent label such as green fluorescent protein used in a fusion. This assay can be used to screen for compounds or protocols that disrupt binding to the microsomal membrane by conducting the assay in the presence and absence of the protocols or compounds and comparing the results.

In addition to the above-described methods that can be conducted extracellularly, the effect of various protocols and compounds or mixtures of compounds on the behavior in terms of binding to cytoplasmic membranes of the relevant amphipathic helix can be determined in a variety of intracellular assays. Any eukaryotic cells may be used, but typically and most conveniently, mammalian cells or yeast cells are used in these assays.

Intracellular assays can be performed by generating desired peptide constructs intracellularly from recombinant expression systems. Alternatively, the assays can be conducted by first preparing the labeled amphipathic helix or protein containing said helix and introducing the derivatized helix into the cells using cell-penetrating peptides. The compounds to be tested may be introduced in the same manner. Such cell-penetrating peptides are described, for example, in a review article by Lindgrin, M., et al., in TiPS (2000) 21:99-103, the contents of which are incorporated herein by reference to describe an exemplary list of such cell-penetrating peptides. These peptides can be coupled to any substance to facilitate the entry of said substance into a eukaryotic cell.

In another embodiment, MTS is able to transport both peptides and full-length proteins into the cytoplasm of cells with or without covalent linkage or crosslinking. (For example, Reference 14.) It is believed that the separate peptides form a noncovalent complex in solution that is then transported into the cell. In one embodiment, the peptides are NS4B or NS5A.

The ability to deliver peptides and proteins into the intracellular milieu for investigational studies or therapeutic applications has previously been limited by the lack of consistent and efficient uptake across the cell membrane. However, a number of reports in the last couple of years have identified various membrane translocation sequences (For example, see references 10, 13, 14, 16, 17, 20, 21, 22) that allow the transduction of peptides across the plasma membrane. The mechanism of transduction is not yet clear, but it has been shown that it is not due to receptor-mediated uptake, or in conjunction with a known transport mechanism. In the initial reports, the MTS was covalently linked to the peptide or protein that was to be delivered into the cell, but recently an MTS was identified that was able to transport both peptides and full-length proteins into the cytoplasm of cells in the absence of covalent linkage or crosslinking (14). Apparently, the separate peptides form a noncovalent complex in solution that is then transported into the cell.

In the most direct forms of such assays, the change in intracellular distribution of the labeled amphipathic helix either supplied per se or in the context of a larger protein can be determined. A wide variety of labels can be used; perhaps the most convenient is a fusion with green fluorescent protein, or simple coupling of the amphipathic helix or the protein containing it to a detectable fluorescent label. The location of the labeled helix or protein containing it can then be observed by a variety of methods including direct observation and histological techniques. Thus, in one example, the effect of a candidate compound or protocol directly on the ability of the helix to bind to cellular membranes can be assessed by coupling the helix to a reporter which is detectable; most convenient are labels which are fusion proteins formed with the helix, such as green fluorescent protein. The intracellular locations of the reporter in the presence and absence of the candidate protocol compound can then be compared. The corresponding labeled helix, which has been mutated to disrupt the amphipathic helical conformation, can conveniently be used as a control. Compounds or protocols that are able to disrupt the binding of the helix with the membrane can readily be identified when their presence results in less label associated with cell membranes.

If histological techniques are used, the label can be less direct; for example, the helix might be fused to a protein that can be detected with a labeled antibody or may be fused to an enzyme that can be detected in the presence of a substrate. Once the cells are fixed histologically, the supplementary reagents can be added for detection.

Another embodiment of this uses cells harboring a vector or plasmid expression NS5A or HCV replicon with a wild-type amphipathic helix in NS5A. The cells are exposed to a control or candidate inhibitor. At the end of the assay, the cells are fixed and stained for NS5A by indirect immunofluorescence. A compound is deemed inhibitory if it alters the normal membrane associated staining of NS5A.

Test compounds that appear to interrupt the ability of the amphipathic helix to bind to the cellular membranes, or which are shown to disrupt the normal binding pattern of the amphipathic helix can be confirmed as anti-HCV agents in a standard colony formation assay. In this assay, an HCV replicon is supplied with a drug resistance marker, such as neomycin resistance. When neomycin-sensitive cells are infected with the replicon and grown on neomycin-containing medium or G418, for example, only cells wherein replication can occur will be able to form colonies. The diagnostic replicon can be used to infect neomycin-sensitive cells in the presence and absence of the compound that has been shown to disrupt the amphipathic helix/membrane binding, and such compounds result in destroying or decreasing the ability of the infected cells to form colonies. Alternatively, RNA replicon levels can be measured to identify the effect of the compound.

When intracellular formats are used, in addition to testing compounds and mixtures of compounds, as noted above, it is possible to test the effect of protocols which involve various regimes of treatment, including, in addition to providing compounds, various antisense techniques, and various forms of environmental stress such as pH changes, temperature changes, mechanical disturbances and the like.

In addition to the foregoing, somewhat more sophisticated methods to assess the impact of compounds and protocols on the intracellular location of substances containing the amphipathic helices derived from Hepatitis C nonstructural proteins can be employed. For example, it is demonstrated below that disruption of the amphipathic helix in NS5A, in addition to causing the protein to fail to associate with cytoplasmic membranes, directs this protein to the nucleus. Therefore, the assay methods can include features in the substance containing the amphipathic helix that act as nuclear localization signals (NLS), many of which are well known in the art. Under these conditions the label can constitute a functionality which exerts its effect in the nucleus, and the disruption of binding of the amphipathic helix with the cytoplasmic membrane can be detected by a reporter function associated with the helix which exerts its effects in the nucleus. Such effects would be, for example, enhancement or repression of the expression of a detectable protein; this would involve including trans activators, transcription factors, or repressors in the construct containing the helix and the NLS. Of course, the nuclear localization signal—derived constructs can also be detected in the nucleus directly, using a direct detectable label of the sort described above—e.g., GFP, a partner in an antibody/antigen interaction, or an enzymatic activity, or a radiolabel.

For example, in one preferred format, the amphipathic helix or a larger protein comprising said helix is coupled to a nuclear localization signal and to a transactivator. The host cell is modified to contain an expression system for a detectable protein, for example, green fluorescent protein in its genome. The transactivator then can effect the expression of the green fluorescent protein under conditions wherein the protocol or compound to be tested disrupts the binding of the amphipathic helix with the cytoplasmic membrane, thus permitting the nuclear localization signal to transport the construct to the nucleus where the transactivator can effect expression of the GFP. Alternative proteins whose expression can be detected are those, such as GFP, that are detectable per se or may be detectable by virtue of their effects on cellular growth, such as his3, leu2, β-galactosidase, β-glucoronidase, SV40T antigen, chloramphenicol acetyl transferase (CAT), hygromycin B phosphotransferase, SEAP or cell surface antigens such as CD4. In addition to transactivators, transcription factors which enhance expression include derivatives of lexA, cI, or gal4 DNA binding domains fused to activation domains of B42, VP16 and the like.

Again, the essential feature is the detection of the effect of the proposed protocol, compounds or mixtures of compounds on the interaction of the amphipathic helix, whether supplied per se or in the context of a larger protein, with the cytoplasmic membranes. The foregoing suggested assay formats are merely exemplary and a wide variety of such formats will be apparent to one of skill in the art. Any such assay method is appropriate; the design of such assays and forms of label draws on a wide literature available to the practitioner.

By conducting the foregoing assays, compounds and/or protocols are identified which will be effective in treating HCV infection. By “treating” is meant both therapeutic and prophylactic treatment, and refers to a desirable effect on viral load, or symptomology, or any desirable outcome which mitigates the negative consequences of the typical progress of HCV infection. The term “treat” is not to be construed to imply absolute cure or absolute prevention. Any helpful amelioration or repression of the infection is sufficient to meet this definition.

Compounds thus identified can be administered in conventional ways using standard pharmaceutical formulations such as those set forth in Remington's Pharmaceutical Sciences, latest edition, Mack Publishing Co., Easton, Pa., incorporated herein by reference. (See also, References 23-33.) Various enteral or parenteral routes of administration may be used, including administering by injection, such as intravenous, intramuscular, subcutaneous and the like, or by oral administration or by suppository. In addition, sustained release compositions can also be used.

The terms “an effective amount,” “an anti-HCV effective amount,” or a “pharmaceutically effective amount” of a peptide of the present invention as applied to such molecules refers to an amount of a peptide, or combination of two or more peptides as disclosed herein, effective in reducing or ameliorating conditions, symptoms, or disorders associated with HCV infection or associated pathogenesis in patients, and/or in reducing viral levels in vitro or in vivo.

Effective amounts of peptides for the treatment or prevention of HCV infections, delivery vehicles containing peptides or constructs encoding the same, agonists, and treatment protocols, can be determined by conventional means. For example, the medical practitioner can commence treatment with a low dose of one or more peptides in a subject or patient in need thereof, and then increase the dosage, or systematically vary the dosage regimen, monitor the effects thereof on the patient or subject, and adjust the dosage or treatment regimen to maximize the desired therapeutic effect. Further discussion of optimization of dosage and treatment regimens can be found in Benet et al., in Goodman & Gilman's The Pharmacological Basis of Therapeutics, Ninth Edition, Hardman et al., Eds., McGraw-Hill, New York, (1996), Chapter 1, pp. 3-27, and L. A. Bauer, in Pharmacotherapy, A Pathophysiologic Approach, Fourth Edition, DiPiro et al., Eds., Appleton & Lange, Stamford, Conn., (1999), Chapter 3, pp. 21-43, and the references cited therein, to which the reader is referred.

The dosage levels and mode of administration will be dependent on the nature of the compound identified and the particular situation of the subject. Optimization of routes of administration, dosage levels, and adjustment of protocols, including monitoring systems to assess effectiveness of the treatment are routine matters well within ordinary skill. Protocols which are identified using the intracellular assays set forth above must, of course, be modified in the context of treatment of subjects, and this, too, falls within the skill of the practitioner.

Typically, the compounds that are identified by the methods of the invention will be “small molecules”—i.e., synthetic organic structures typical of pharmaceuticals. Examples of such “small molecules” are found, for example, in the Physicians' Desk Reference (with respect to approved drugs), the Merck Index, and the U.S. Pharmacopoeia. However, such compounds may also include peptides, peptidomimetics, nucleic acids, peptide nucleic acids, carbohydrates, lipids, and the like. As noted above, the HCV nonstructural protein amphipathic helix used in these assays may be the native helix, both alone and in the context of a larger protein and the assays may also utilize a homologous form of the helix included within the definition above which retains the spatial and charge configuration of the native form.

In addition to compounds identified by means of the foregoing assays, protocols and substances useful in treating HCV infection can be formulated and utilized a priori. For example, the helix itself, or a functional fragment thereof can readily be used in treatment by virtue of its ability to bind the helix as it resides in an HCV non-structural protein itself or to compete with the helix as it resides in an HCV non-structural protein itself for sites on the cytoplasmic membrane to which the helix will bind. Thus, formulations of the HCV nonstructural protein amphipathic helix or functional fragment thereof can be used directly to treat HCV infection. Typically, these formulations will contain peptides bearing the helix of less than 60 amino acids, in another embodiment less than 50 amino acids, in another embodiment less than 30 amino acids, and, in yet another embodiment less than 25 amino acids in another embodiment, not be less than 4 amino acids, and may, in addition to the peptide region bearing the helix, further contain components to enhance membrane penetration. The peptides comprising the helix may be as short as 10-15 amino acids, 6-9 amino acids or 4-6 amino acids, so long as functionality in terms of competitive binding, or inhibition of binding, is retained. Methods to synthesize such peptides are, of course, well known, both direct and recombinant methods may be used. Thus, a peptide useful in the method of the invention as to its helix-based antiviral activity will typically contain from about 4 to 60 amino acids, and certainly far less than the several hundred amino acids contained in the native viral protein from which it can be derived. This relatively short peptide may optionally be coupled to additional sequence either for labeling, or, more typically, for conferring the ability to enter cells. Such membrane penetration facilitators are known, for example, the HIV-tat peptide or MTSs described herein, are able to introduce non-native proteins into cells. The peptides to be administered will thus contain a portion comprising the amphipathic helix and a heterologous portion for facilitating cellular entry. Entry can also be facilitated by liposomes or cationic polymers, for example. However, wild type NS5A is able to cross the membrane without the assistance of a facilitator. Wild type NS5A is capable of entering the cell without any previously described MTS peptide or other facilitator.

As used herein “functional” refers to a protein, peptide, helix or antibody, or fragment thereof, which possesses the ability to inhibit the binding of a nonstructural HCV protein, for example, NS4B or NS5A, to a cell membrane.

The peptides useful in the methods of the invention can also be generated in the subject to be treated by virtue of administering expression systems for those peptides consisting entirely of gene-encoded amino acids. These expression systems may be introduced as naked DNA, as expression vectors suitable for transfection of mammalian cells, or preferably using adenoviral or retroviral or other suitable viral vectors.

As described above, however, these competitor peptides need not be the native sequences per se and need not even be peptides per se, but may contain isosteric linkages or other polymeric features that result in similar charge/shape features as compared to the native helices.

Peptides, or compounds with similar charge/shape features and having the activity of the peptides described herein, can be identified by phage display using wild-type amphipathic helix and a mutant amphipathic helix peptides as positive and negative selectors, respectively.

The compositions or agents of the invention may comprise, consist essentially of, or consist of the peptide sequences disclosed herein. The phrase “consists essentially of or consisting essentially of” or the like, when applied to anti-HCV peptides encompassed by the present invention refers to peptide sequences like those disclosed herein, but which contain additional amino acids (or analogs or derivatives thereof as discussed above). Such additional amino acids, etc., however, do not materially affect the basic and novel characteristic(s) of these peptides in modulating, attenuating, or inhibiting HCV infection, replication, and/or pathogenesis, including the specific quantitative effects of these peptides, compared to those of the corresponding peptides disclosed herein.

In one approach, the agent may be a transdominant inhibitor of the membrane association function whereby forms of the amphipathic helix that interfere with the ability of the helix to form oligomers can be used. Thus, by generating or providing a mutant form of the helix containing one or more amino acid substations, this form may associate with the native helix to provide an inactive form or rendering it unable to dimerize or oligomerize with additional native forms. In one approach, the decoy peptide is mutated to convert hydrophobic amino acids to hydrophilic ones thus destroying the hydrophobic face of the helix. For example, mutated versions of the peptide sequence for NS5A strains would include SGSWLRDDWDWECEVLSDDKTWLKAK (SEQ ID NO: 15) or SGSWLRDDWDWECTVLTDDKTWLQSKL (SEQ ID NO: 16). SEQ ID NOS: 15 and 16 are used as PEP2 in Example 4, below.

In another approach, the agent is a competitive inhibitor of the amphipathic helix. These competitive inhibitors may interrupt the binding between the helix and the membrane, achieving the desired effect. Such inhibitors may be fragments of the wild type sequence of the amphipathic sequence or variants or mutants thereof. Fragments of the HCV nonstructural proteins that may be used as competitive inhibitors may include, but are not limited to:

(SEQ ID NO: 462) YIEQGMMLAEQFKQKALGLLQTASRHAEV (NS4B 6-34), (SEQ ID NO: 3) QDVLKEVKAAASKVKANLLSVEE (NS5B 65-87), and (SEQ ID NO: 4) DVRCHARKAVAHINSVWKD (NS5B107-125).

Another competitive inhibitor of NS5A would include: SGSWLRDVWDWICTVLTDFKTWLQSKL (SEQ ID NO: 14) and variants and mutants thereof. Variants and mutants of this peptide would include a peptide with one or more of the following amino acid substitutions: substitution of L at amino acid 16 by A or K; or substitution of the T at amino acid 17 by A; or substitution of the D at amino acid 18 by A; or substitution of the F at amino acid 19 by A; or substitution of the K at amino acid 20 by A; or substitution of the W at amino acid 22 by A; or substitution of the L at amino acid 23 by K, and derivatives thereof. Another such mutant of NSSA is: SGSX₁X₂X₃X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃X₁₄X₁₅X₁₆X₁₇X₁₈X₁₉X₂₀QSK L (SEQ ID NO:467), where X₁ is W, A or F; X2 is L, A or K; X3 is R, A or N; X4 is D, A or S; X₅ iS V, I, D or S; X₆ is W, A or F; X₇ is D, A or S; X₈ is W, A or F; X₉ is I, E or L; X₁₀ is C, A or S; X₁₁ is T, E, A or W; X₁₂ is V, D or S; X₁₃ is L, A or K; X₁₄ is T,S, A or W; X₁₅ is D, A or S; X₁₆ is F, D, or L; X₁₇ is K, A or L; X₁₈ is T, A or W; X₁₉ is W, A or F; and X₂₀ is L, A or K. In another embodiment, X₁, X₂, X₄, X₆, X₈, X₁₀, X₁₃, X₁₅, X₁₆ or X₂₀ may be D or X₁₆ is A. Where the agent is a competitive inhibitor, some of the above mutations would enhance the inhibitory activity of the peptide, others would completely or partially abolish the inhibitory activity of the peptide. Mutations may be observed alone or in combination, for example, any one substitution, X₁₋₂₀, occurs within the context of the wild type sequence at any one time, a combination of two mutations such as: X₅ and X₉, X₅ and X₁₆, or X₉ and X₁₆ or three mutations are found in the same peptide, X₅, with X₉, and X₁₆. Additional mutations of the above inhibitor may include the sequence:

X₁X₂DVWDWICTX₃X₄X₅X₆X₇X₈X₉ (SEQ ID NO:468) wherein when X₁ and X₂ are present, X₁ is L and X₂ is R; wherein X₁ and X₂ are present, X₃, X₄, X₅, X₆, X₇, X₈ and X₉ are optionally present, and when X₃, X₄, X₅, X₆, X₇, X₈ and X₉ are present, X₃ is V, X₄ is L, X₅ is T, X₆ is D, X₇ is F, X₈ is K and X₉ is T; and wherein X₆ is present, X3, X₄ and X₅ are all present, wherein X₆ is D, X₃ is V, X₄ is L, and X₅ is T. In particular where the sequence is LRDVWDWICTVLTDFKT (SEQ ID NO: 463), LRDVWDWICT (SEQ ID NO: 464) or DVWDWICTVLTD (SEQ ID NO: 465). In another embodiment, the competitive inhibitor may be SWLRDVWDWIC (SEQ ID NO: 466).

A mutant, and competitive inhibitor, of NS4B may include the sequence: X₂X₃X₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃X₁₄X₁₅X₁₆X₁₇X₁₈X₁₉X₂₀X₂₁X₂₂X₂₃X₂₄X₂₅X₂₆X₂₇ X₂₈X₂₉ where X₁ is Y, A or H; X₂ is I, E or L; X₃ is E, A or Q; X₄ is Q, V or R; X₅ is G, A or D; X₆ is M, E or C; X₇ is M, E or C; X₈ is L, E or Q; X₉ is A, D or S; X₁₀ is E, A or Q; X₁₁ is Q, V or R; X₁₂ is F, D or L; X₁₃ is K, I or Q; X₁₄ is Q, V Or R; X₁₅ is K, I or Q; X₁₆ is A, D or G; X₁₇ is L, A or K; X₁₈ is G, E or S; X₁₉ is L, A or K; X₂₀ is L, A or K; X₂₁ is Q, V or R; X₂₂ is T, A or W; X₂₃ is A, D or G; X₂₄ is S, D or A; X₂₅ is R, L or W; X₂₆ is Q, V or R; X₂₇ is A, D or G; and X₂₈ is E, A or Q.

While the majority of the above mutations and substitutions are conservative (i.e. wild type hydrophobic residues are substituted with additional hydrophobic residues (for example, A to F), charged residues are substituted with similarly charged residues, etc.), it is noted that nonconservative substitutions may also be performed. For example, where a wild type hydrophobic residue is substituted with a hydrophilic residue, or a negatively charged residue (for example, D) is substituted with a positively charged residue (for example, K).

Where the agent is a competitive inhibitor, some of the above mutations would enhance the inhibitory activity of the peptide, others would completely or partially abolish the inhibitory activity of the peptide. Mutations may be observed alone or in combination, for example, any one substitution, X₁₋₂₈, occurs within the context of the wild type sequence at any one time, a combination of two mutations such as: X₂ and X₅, X₂ and X₁₉, or X₅ and X₁₉ or three mutations are found in the same peptide, X₂, with X₅, and X₁₉.

In another embodiment, the agent may be a complementary peptide to the helix. Complementary peptides may interrupt the binding between the helix and the membrane, achieving the desired effect. Such complementary peptides may also inhibit the formation of the amphipathic helix, may interact or bind to the helix to inhibit binding of the helix to cellular membranes, or may otherwise inhibit the amphipathic helices.

For example, the HCV genomic RNA sequence that codes for the NS4B amphipathic helix in the HCV genotype 1A sequence is:

(SEQ ID NO: 17) UACAUCGAGCAAGGGAUGAUGCUCGCTGAGCAGUUCAAGCAGAAGGCCC UCGGCCUCCUGCAGACCGCGUCCCGCCAAGCAGAG. (Kolykhalov, A. A. and Rice, C. M., Science 277 (5325), 570-574 (1997); GenBank Accession No.: AF009606.) The protein translation of the above sequence is: YIEQGMMLAEQFKQKALGLLQTASRQAE (SEQ ID NO: 18). The reverse complement cDNA sequence corresponding to the HCV genomic RNA sequence that codes for the NS4B amphipathic helix (GenBank Accession No.: AF009606) is: CTCTGCTTGGCGGGACGCGGTCTGCAGGAGGCCGAGGGCCTTCTGCTTGA ACTGCTCAGCGAGCATCATCCCTTGCTCGATGTA (SEQ ID NO: 19). The complementary peptide translated from the reverse complement sequence is: LCLAGRGLQEAEGLLLELLSEHHPLLDV (SEQ ID NO: 20). This complementary peptide, as a whole, or in part, may be active as an HCV antiviral or may be useful in the prediction of small molecules that are HCV antivirals. In one embodiment a fragment of this complementary peptide comprising 6-27 amino acids may be used in the discovery of HCV antivirals. Table 1 sets forth exemplary peptides (SEQ ID NOS: 21-295) of this embodiment.

TABLE 1 All smaller NS4B complementary  peptides with 6 or more amino acids: Sequence Identification Sequence Number LQEAEG SEQ ID NO: 21 CLAGRG SEQ ID NO: 22 LELLSE SEQ ID NO: 23 GLQEAE SEQ ID NO: 24 LLELLS SEQ ID NO: 25 QEAEGL SEQ ID NO: 26 RGLQEA SEQ ID NO: 27 LAGRGL SEQ ID NO: 28 GRGLQE SEQ ID NO: 29 ELLSEH SEQ ID NO: 30 LLLELL SEQ ID NO: 31 LCLAGR SEQ ID NO: 32 HPLLDV SEQ ID NO: 33 AEGLLL SEQ ID NO: 34 AGRGLQ SEQ ID NO: 35 EAEGLL SEQ ID NO: 36 LSEHHP SEQ ID NO: 37 HHPLLD SEQ ID NO: 38 EGLLLE SEQ ID NO: 39 SEHHPL SEQ ID NO: 40 LLSEHH SEQ ID NO: 41 EHHPLL SEQ ID NO: 42 GLLLEL SEQ ID NO: 43 LELLSEH SEQ ID NO: 44 ELLSEHH SEQ ID NO: 45 LLELLSE SEQ ID NO: 46 LLSEHHP SEQ ID NO: 47 HHPLLDV SEQ ID NO: 48 GLLLELL SEQ ID NO: 49 LAGRGLQ SEQ ID NO: 50 LSEHHPL SEQ ID NO: 51 LCLAGRG SEQ ID NO: 52 LQEAEGL SEQ ID NO: 53 AGRGLQE SEQ ID NO: 54 AEGLLLE SEQ ID NO: 55 GRGLQEA SEQ ID NO: 56 RGLQEAE SEQ ID NO: 57 QEAEGLL SEQ ID NO: 58 SEHHPLL SEQ ID NO: 59 EHHPLLD SEQ ID NO: 60 GLQEAEG SEQ ID NO: 61 EGLLLEL SEQ ID NO: 62 LLLELLS SEQ ID NO: 63 EAEGLLL SEQ ID NO: 64 CLAGRGL SEQ ID NO: 65 CLAGRGLQ SEQ ID NO: 66 QEAEGLLL SEQ ID NO: 67 LAGRGLQE SEQ ID NO: 68 LCLAGRGL SEQ ID NO: 69 AGRGLQEA SEQ ID NO: 70 LLLELLSE SEQ ID NO: 71 LELLSEHH SEQ ID NO: 72 AEGLLLEL SEQ ID NO: 73 EGLLLELL SEQ ID NO: 74 LLSEHHPL SEQ ID NO: 75 GRGLQEAE SEQ ID NO: 76 EAEGLLLE SEQ ID NO: 77 RGLQEAEG SEQ ID NO: 78 LLELLSEH SEQ ID NO: 79 SEHHPLLD SEQ ID NO: 80 LSEHHPLL SEQ ID NO: 81 LQEAEGLL SEQ ID NO: 82 ELLSEHHP SEQ ID NO: 83 GLLLELLS SEQ ID NO: 84 EHHPLLDV SEQ ID NO: 85 GLQEAEGL SEQ ID NO: 86 LLSEHHPLL SEQ ID NO: 87 LELLSEHHP SEQ ID NO: 88 RGLQEAEGL SEQ ID NO: 89 ELLSEHHPL SEQ ID NO: 90 LCLAGRGLQ SEQ ID NO: 91 AGRGLQEAE SEQ ID NO: 92 GLLLELLSE SEQ ID NO: 93 LSEHHPLLD SEQ ID NO: 94 EGLLLELLS SEQ ID NO: 95 GLQEAEGLL SEQ ID NO: 96 AEGLLLELL SEQ ID NO: 97 QEAEGLLLE SEQ ID NO: 98 SEHHPLLDV SEQ ID NO: 99 LLLELLSEH SEQ ID NO: 100 GRGLQEAEG SEQ ID NO: 101 CLAGRGLQE SEQ ID NO: 102 EAEGLLLEL SEQ ID NO: 103 LAGRGLQEA SEQ ID NO: 104 LLELLSEHH SEQ ID NO: 105 LQEAEGLLL SEQ ID NO: 106 LSEHHPLLDV SEQ ID NO: 107 LELLSEHHPL SEQ ID NO: 108 RGLQEAEGLL SEQ ID NO: 109 LLSEHHPLLD SEQ ID NO: 110 AEGLLLELLS SEQ ID NO: 111 GLQEAEGLLL SEQ ID NO: 112 EGLLLELLSE SEQ ID NO: 113 LCLAGRGLQE SEQ ID NO: 114 LLLELLSEHH SEQ ID NO: 115 EAEGLLLELL SEQ ID NO: 116 GLLLELLSEH SEQ ID NO: 117 ELLSEHHPLL SEQ ID NO: 118 GRGLQEAEGL SEQ ID NO: 119 LQEAEGLLLE SEQ ID NO: 120 LLELLSEHHP SEQ ID NO: 121 CLAGRGLQEA SEQ ID NO: 122 QEAEGLLLEL SEQ ID NO: 123 AGRGLQEAEG SEQ ID NO: 124 LAGRGLQEAE SEQ ID NO: 125 LLELLSEHHPL SEQ ID NO: 126 CLAGRGLQEAE SEQ ID NO: 127 RGLQEAEGLLL SEQ ID NO: 128 LAGRGLQEAEG SEQ ID NO: 129 LQEAEGLLLEL SEQ ID NO: 130 LLLELLSEHHP SEQ ID NO: 131 ELLSEHHPLLD SEQ ID NO: 132 AGRGLQEAEGL SEQ ID NO: 133 LLSEHHPLLDV SEQ ID NO: 134 LCLAGRGLQEA SEQ ID NO: 135 GLLLELLSEHH SEQ ID NO: 136 LELLSEHHPLL SEQ ID NO: 137 QEAEGLLLELL SEQ ID NO: 138 EGLLLELLSEH SEQ ID NO: 139 GRGLQEAEGLL SEQ ID NO: 140 AEGLLLELLSE SEQ ID NO: 141 GLQEAEGLLLE SEQ ID NO: 142 EAEGLLLELLS SEQ ID NO: 143 EGLLLELLSEHH SEQ ID NO: 144 RGLQEAEGLLLE SEQ ID NO: 145 GLLLELLSEHHP SEQ ID NO: 146 LQEAEGLLLELL SEQ ID NO: 147 GLQEAEGLLLEL SEQ ID NO: 148 LAGRGLQEAEGL SEQ ID NO: 149 GRGLQEAEGLLL SEQ ID NO: 150 QEAEGLLLELLS SEQ ID NO: 151 AEGLLLELLSEH SEQ ID NO: 152 AGRGLQEAEGLL SEQ ID NO: 153 LELLSEHHPLLD SEQ ID NO: 154 LCLAGRGLQEAE SEQ ID NO: 155 LLLELLSEHHPL SEQ ID NO: 156 LLELLSEHHPLL SEQ ID NO: 157 ELLSEHHPLLDV SEQ ID NO: 158 EAEGLLLELLSE SEQ ID NO: 159 CLAGRGLQEAEG SEQ ID NO: 160 CLAGRGLQEAEGL SEQ ID NO: 161 RGLQEAEGLLLEL SEQ ID NO: 162 LLELLSEHHPLLD SEQ ID NO: 163 GRGLQEAEGLLLE SEQ ID NO: 164 LCLAGRGLQEAEG SEQ ID NO: 165 LELLSEHHPLLDV SEQ ID NO: 166 EGLLLELLSEHHP SEQ ID NO: 167 EAEGLLLELLSEH SEQ ID NO: 168 GLQEAEGLLLELL SEQ ID NO: 169 AGRGLQEAEGLLL SEQ ID NO: 170 AEGLLLELLSEHH SEQ ID NO: 171 LAGRGLQEAEGLL SEQ ID NO: 172 QEAEGLLLELLSE SEQ ID NO: 173 LLLELLSEHHPLL SEQ ID NO: 174 LQEAEGLLLELLS SEQ ID NO: 175 GLLLELLSEHHPL SEQ ID NO: 176 EAEGLLLELLSEHH SEQ ID NO: 177 EGLLLELLSEHHPL SEQ ID NO: 178 AGRGLQEAEGLLLE SEQ ID NO: 179 LCLAGRGLQEAEGL SEQ ID NO: 180 GLLLELLSEHHPLL SEQ ID NO: 181 QEAEGLLLELLSEH SEQ ID NO: 182 RGLQEAEGLLLELL SEQ ID NO: 183 LLLELLSEHHPLLD SEQ ID NO: 184 LQEAEGLLLELLSE SEQ ID NO: 185 LLELLSEHHPLLDV SEQ ID NO: 186 GLQEAEGLLLELLS SEQ ID NO: 187 GRGLQEAEGLLLEL SEQ ID NO: 188 AEGLLLELLSEHHP SEQ ID NO: 189 CLAGRGLQEAEGLL SEQ ID NO: 190 LAGRGLQEAEGLLL SEQ ID NO: 191 LLLELLSEHHPLLDV SEQ ID NO: 192 AGRGLQEAEGLLLEL SEQ ID NO: 193 AEGLLLELLSEHHPL SEQ ID NO: 194 GLLLELLSEHEPLLD SEQ ID NO: 195 LQEAEGLLLELLSEH SEQ ID NO: 196 GLQEAEGLLLELLSE SEQ ID NO: 197 LCLAGRGLQEAEGLL SEQ ID NO: 198 EAEGLLLELLSEHHP SEQ ID NO: 199 GRGLQEAEGLLLELL SEQ ID NO: 200 QEAEGLLLELLSEHH SEQ ID NO: 201 LAGRGLQEAEGLLLE SEQ ID NO: 202 CLAGRGLQEAEGLLL SEQ ID NO: 203 EGLLLELLSEHHPLL SEQ ID NO: 204 RGLQEAEGLLLELLS SEQ ID NO: 205 LAGRGLQEAEGLLLEL SEQ ID NO: 206 GLLLELLSEHHPLLDV SEQ ID NO: 207 GRGLQEAEGLLLELLS SEQ ID NO: 208 AGRGLQEAEGLLLELL SEQ ID NO: 209 GLQEAEGLLLELLSEH SEQ ID NO: 210 RGLQEAEGLLLELLSE SEQ ID NO: 211 LQEAEGLLLELLSEHH SEQ ID NO: 212 CLAGRGLQEAEGLLLE SEQ ID NO: 213 QEAEGLLLELLSEHHP SEQ ID NO: 214 AEGLLLELLSEHHPLL SEQ ID NO: 215 EAEGLLLELLSEHHPL SEQ ID NO: 216 LCLAGRGLQEAEGLLL SEQ ID NO: 217 EGLLLELLSEHHPLLD SEQ ID NO: 218 LCLAGRGLQEAEGLLLE SEQ ID NO: 219 QEAEGLLLELLSEHHPL SEQ ID NO: 220 EAEGLLLELLSEHHPLL SEQ ID NO: 221 RGLQEAEGLLLELLSEH SEQ ID NO: 222 CLAGRGLQEAEGLLLEL SEQ ID NO: 223 GRGLQEAEGLLLELLSE SEQ ID NO: 224 LAGRGLQEAEGLLLELL SEQ ID NO: 225 AGRGLQEAEGLLLELLS SEQ ID NO: 226 GLQEAEGLLLELLSEHH SEQ ID NO: 227 EGLLLELLSEHHPLLDV SEQ ID NO: 228 AEGLLLELLSEHHPLLD SEQ ID NO: 229 LQEAEGLLLELLSEHHP SEQ ID NO: 230 CLAGRGLQEAEGLLLELL SEQ ID NO: 231 LQEAEGLLLELLSEHHPL SEQ ID NO: 232 GRGLQEAEGLLLELLSEH SEQ ID NO: 233 EAEGLLLELLSEHHPLLD SEQ ID NO: 234 AEGLLLELLSEHHPLLDV SEQ ID NO: 235 GLQEAEGLLLELLSEHHP SEQ ID NO: 236 RGLQEAEGLLLELLSEHH SEQ ID NO: 237 QEAEGLLLELLSEHHPLL SEQ ID NO: 238 LAGRGLQEAEGLLLELLS SEQ ID NO: 239 LCLAGRGLQEAEGLLLEL SEQ ID NO: 240 AGRGLQEAEGLLLELLSE SEQ ID NO: 241 AGRGLQEAEGLLLELLSEH SEQ ID NO: 242 GLQEAEGLLLELLSEHHPL SEQ ID NO: 243 GRGLQEAEGLLLELLSEHH SEQ ID NO: 244 LCLAGRGLQEAEGLLLELL SEQ ID NO: 245 CLAGRGLQEAEGLLLELLS SEQ ID NO: 246 RGLQEAEGLLLELLSEHHP SEQ ID NO: 247 LAGRGLQEAEGLLLELLSE SEQ ID NO: 248 QEAEGLLLELLSEHHPLLD SEQ ID NO: 249 LQEAEGLLLELLSEHHPLL SEQ ID NO: 250 EAEGLLLELLSEHHPLLDV SEQ ID NO: 251 RGLQEAEGLLLELLSEHHPL SEQ ID NO: 252 GLQEAEGLLLELLSEHHPLL SEQ ID NO: 253 AGRGLQEAEGLLLELLSEHH SEQ ID NO: 254 LAGRGLQEAEGLLLELLSEH SEQ ID NO: 255 GRGLQEAEGLLLELLSEHHP SEQ ID NO: 256 LCLAGRGLQEAEGLLLELLS SEQ ID NO: 257 LQEAEGLLLELLSEHHPLLD SEQ ID NO: 258 QEAEGLLLELLSEHHPLLDV SEQ ID NO: 259 CLAGRGLQEAEGLLLELLSE SEQ ID NO: 260 LCLAGRGLQEAEGLLLELLSE SEQ ID NO: 261 RGLQEAEGLLLELLSEHHPLL SEQ ID NO: 262 LQEAEGLLLELLSEHHPLLDV SEQ ID NO: 263 GRGLQEAEGLLLELLSEHHPL SEQ ID NO: 264 AGRGLQEAEGLLLELLSEHHP SEQ ID NO: 265 LAGRGLQEAEGLLLELLSEHH SEQ ID NO: 266 CLAGRGLQEAEGLLLELLSEH SEQ ID NO: 267 GLQEAEGLLLELLSEHHPLLD SEQ ID NO: 268 GLQEAEGLLLELLSEHHPLLDV SEQ ID NO: 269 AGRGLQEAEGLLLELLSEHHPL SEQ ID NO: 270 CLAGRGLQEAEGLLLELLSEHH SEQ ID NO: 271 GRGLQEAEGLLLELLSEHHPLL SEQ ID NO: 272 RGLQEAEGLLLELLSEHHPLLD SEQ ID NO: 273 LAGRGLQEAEGLLLELLSEHHP SEQ ID NO: 274 LCLAGRGLQEAEGLLLELLSEH SEQ ID NO: 275 CLAGRGLQEAEGLLLELLSEHHP SEQ ID NO: 276 GRGLQEAEGLLLELLSEHHPLLD SEQ ID NO: 277 LCLAGRGLQEAEGLLLELLSEHH SEQ ID NO: 278 LAGRGLQEAEGLLLELLSEHHPL SEQ ID NO: 279 RGLQEAEGLLLELLSEHHPLLDV SEQ ID NO: 280 AGRGLQEAEGLLLELLSEHHPLL SEQ ID NO: 281 AGRGLQEAEGLLLELLSEHHPLLD SEQ ID NO: 282 CLAGRGLQEAEGLLLELLSEHHPL SEQ ID NO: 283 LCLAGRGLQEAEGLLLELLSEHHP SEQ ID NO: 284 GRGLQEAEGLLLELLSEHHPLLDV SEQ ID NO: 285 LAGRGLQEAEGLLLELLSEHHPLL SEQ ID NO: 286 AGRGLQEAEGLLLELLSEHHPLLDV SEQ ID NO: 287 LCLAGRGLQEAEGLLLELLSEHHPL SEQ ID NO: 288 LAGRGLQEAEGLLLELLSEHHPLLD SEQ ID NO: 289 CLAGRGLQEAEGLLLELLSEHHPLL SEQ ID NO: 290 LCLAGRGLQEAEGLLLELLSEHHPLL SEQ ID NO: 291 LAGRGLQEAEGLLLELLSEHHPLLDV SEQ ID NO: 292 CLAGRGLQEAEGLLLELLSEHHPLLD SEQ ID NO: 293 LCLAGRGLQEAEGLLLELLSEHHPLLD SEQ ID NO: 294 CLAGRGLQEAEGLLLELLSEHHPLLDV SEQ ID NO: 295

In a particular embodiment, the complementary peptides of the invention are used, in whole or in part, in the prediction of small molecules that are HCV antivirals. “Small molecule” as defined above, may include synthetic organic structures typical of pharmaceuticals, and may also include peptides, nucleic acids, peptide nucleic acids, carbohydrates, lipids, and the like. Additionally, small molecules, as used herein, may include chemically synthesized peptidomimetics of the 6-mer to 9-mer peptides of the invention.

Additionally, the HCV genomic RNA sequence that codes for the NS5A amphipathic helix in the HCV genotype 1A sequence is:

UGGCUAAGGGACAUCUGGGACUGGAUAUGCGAGGUGCUGAGCGACUUU AAGACCUGGCUGAAAGCCAAGCUC (SEQ ID NO: 296). (Kolykhalov, A. A. and Rice, C. M., Science 277 (5325), 570-574 (1997); GenBank Accession No.: AF009606.) The protein translation of the above sequence is: WLRDIWDWICEVLSDFKTWLKAKL (SEQ ID NO: 297). The reverse complement cDNA sequence corresponding to the HCV genomic RNA sequence that codes for the NS5A amphipathic helix (GenBank Accession No.: AF009606) is: GAGCTTGGCTTTCAGCCAGGTCTTAAAGTCGCTCAGCACCTCGCATATCCA GTCCCAGATGTCCCTTAGCCA (SEQ ID NO: 298). This reverse complement sequence contains a stop codon at codon 23. The complementary peptide translated from the reverse complement sequence is: ELGFQPGLKVAQHLAYPVPDVP (SEQ ID NO: 299). This complementary peptide, as a whole, or in part, may be active as an HCV antiviral or may be useful in the prediction of small molecules that are HCV antivirals. In one embodiment a fragment of this complementary peptide comprising 6-21 amino acids may is used in the discovery of HCV antivirals. Table 2 sets forth exemplary peptides (SEQ ID NOS: 300-451) of this embodiment.

TABLE 2 NS5A complementary peptides  with 6 or more amino acids: Sequence Identification Sequence Number AQHLAY SEQ ID NO: 300 LGFQPG SEQ ID NO: 301 GLKVAQ SEQ ID NO: 302 ELGFQP SEQ ID NO: 303 PVPDVP SEQ ID NO: 304 FQPGLK SEQ ID NO: 305 GFQPGL SEQ ID NO: 306 VAQHLA SEQ ID NO: 307 LKVAQH SEQ ID NO: 308 HLAYPV SEQ ID NO: 309 KVAQHL SEQ ID NO: 310 QPGLKV SEQ ID NO: 311 LAYPVP SEQ ID NO: 312 YPVPDV SEQ ID NO: 313 QHLAYP SEQ ID NO: 314 PGLKVA SEQ ID NO: 315 AYPVPD SEQ ID NO: 316 QPGLKVA SEQ ID NO: 317 ELGFQPG SEQ ID NO: 318 HLAYPVP SEQ ID NO: 319 LAYPVPD SEQ ID NO: 320 AQHLAYP SEQ ID NO: 321 FQPGLKV SEQ ID NO: 322 KVAQHLA SEQ ID NO: 323 LGFQPGL SEQ ID NO: 324 AYPVPDV SEQ ID NO: 325 PGLKVAQ SEQ ID NO: 326 LKVAQHL SEQ ID NO: 327 GLKVAQH SEQ ID NO: 328 VAQHLAY SEQ ID NO: 329 GFQPGLK SEQ ID NO: 330 QHLAYPV SEQ ID NO: 331 YPVPDVP SEQ ID NO: 332 AYPVPDVP SEQ ID NO: 333 PGLKVAQH SEQ ID NO: 334 QHLAYPVP SEQ ID NO: 335 LAYPVPDV SEQ ID NO: 336 LKVAQHLA SEQ ID NO: 337 GLKVAQHL SEQ ID NO: 338 GFQPGLKV SEQ ID NO: 339 AQHLAYPV SEQ ID NO: 340 VAQHLAYP SEQ ID NO: 341 KVAQHLAY SEQ ID NO: 342 ELGFQPGL SEQ ID NO: 343 LGFQPGLK SEQ ID NO: 344 FQPGLKVA SEQ ID NO: 345 HLAYPVPD SEQ ID NO: 346 QPGLKVAQ SEQ ID NO: 347 ELGFQPGLK SEQ ID NO: 348 VAQHLAYPV SEQ ID NO: 349 LGFQPGLKV SEQ ID NO: 350 QPGLKVAQH SEQ ID NO: 351 KVAQHLAYP SEQ ID NO: 352 PGLKVAQHL SEQ ID NO: 353 FQPGLKVAQ SEQ ID NO: 354 GLKVAQHLA SEQ ID NO: 355 LAYPVPDVP SEQ ID NO: 356 HLAYPVPDV SEQ ID NO: 357 GFQPGLKVA SEQ ID NO: 358 AQHLAYPVP SEQ ID NO: 359 QHLAYPVPD SEQ ID NO: 360 LKVAQHLAY SEQ ID NO: 361 QPGLKVAQHL SEQ ID NO: 362 PGLKVAQHLA SEQ ID NO: 363 HLAYPVPDVP SEQ ID NO: 364 GLKVAQHLAY SEQ ID NO: 365 VAQHLAYPVP SEQ ID NO: 366 KVAQHLAYPV SEQ ID NO: 367 GFQPGLKVAQ SEQ ID NO: 368 QHLAYPVPDV SEQ ID NO: 369 AQHLAYPVPD SEQ ID NO: 370 FQPGLKVAQH SEQ ID NO: 371 ELGFQPGLKV SEQ ID NO: 372 LKVAQHLAYP SEQ ID NO: 373 LGFQPGLKVA SEQ ID NO: 374 QHLAYPVPDVP SEQ ID NO: 375 LKVAQHLAYPV SEQ ID NO: 376 VAQHLAYPVPD SEQ ID NO: 377 PGLKVAQHLAY SEQ ID NO: 378 LGFQPGLKVAQ SEQ ID NO: 379 KVAQHLAYPVP SEQ ID NO: 380 ELGFQPGLKVA SEQ ID NO: 381 GLKVAQHLAYP SEQ ID NO: 382 AQHLAYPVPDV SEQ ID NO: 383 FQPGLKVAQHL SEQ ID NO: 384 QPGLKVAQHLA SEQ ID NO: 385 GFQPGLKVAQH SEQ ID NO: 386 LGFQPGLKVAQH SEQ ID NO: 387 PGLKVAQHLAYP SEQ ID NO: 388 LKVAQHLAYPVP SEQ ID NO: 389 GFQPGLKVAQHL SEQ ID NO: 390 VAQHLAYPVPDV SEQ ID NO: 391 QPGLKVAQHLAY SEQ ID NO: 392 ELGFQPGLKVAQ SEQ ID NO: 393 AQHLAYPVPDVP SEQ ID NO: 394 KVAQHLAYPVPD SEQ ID NO: 395 FQPGLKVAQHLA SEQ ID NO: 396 GLKVAQHLAYPV SEQ ID NO: 397 LGFQPGLKVAQHL SEQ ID NO: 398 VAQHLAYPVPDVP SEQ ID NO: 399 PGLKVAQHLAYPV SEQ ID NO: 400 GFQPGLKVAQHLA SEQ ID NO: 401 LKVAQHLAYPVPD SEQ ID NO: 402 QPGLKVAQHLAYP SEQ ID NO: 403 ELGFQPGLKVAQH SEQ ID NO: 404 GLKVAQHLAYPVP SEQ ID NO: 405 FQPGLKVAQHLAY SEQ ID NO: 406 KVAQHLAYPVPDV SEQ ID NO: 407 ELGFQPGLKVAQHL SEQ ID NO: 408 QPGLKVAQHLAYPV SEQ ID NO: 409 GFQPGLKVAQHLAY SEQ ID NO: 410 LGFQPGLKVAQHLA SEQ ID NO: 411 FQPGLKVAQHLAYP SEQ ID NO: 412 KVAQHLAYPVPDVP SEQ ID NO: 413 PGLKVAQHLAYPVP SEQ ID NO: 414 LKVAQHLAYPVPDV SEQ ID NO: 415 GLKVAQHLAYPVPD SEQ ID NO: 416 GLKVAQHLAYPVPDV SEQ ID NO: 417 PGLKVAQHLAYPVPD SEQ ID NO: 418 ELGFQPGLKVAQHLA SEQ ID NO: 419 LGFQPGLKVAQHLAY SEQ ID NO: 420 GFQPGLKVAQHLAYP SEQ ID NO: 421 QPGLKVAQHLAYPVP SEQ ID NO: 422 FQPGLKVAQHLAYPV SEQ ID NO: 423 LKVAQHLAYPVPDVP SEQ ID NO: 424 FQPGLKVAQHLAYPVP SEQ ID NO: 425 GFQPGLKVAQHLAYPV SEQ ID NO: 426 GLKVAQHLAYPVPDVP SEQ ID NO: 427 PGLKVAQHLAYPVPDV SEQ ID NO: 428 QPGLKVAQHLAYPVPD SEQ ID NO: 429 ELGFQPGLKVAQHLAY SEQ ID NO: 430 LGFQPGLKVAQHLAYP SEQ ID NO: 431 GFQPGLKVAQHLAYPVP SEQ ID NO: 432 FQPGLKVAQHLAYPVPD SEQ ID NO: 433 QPGLKVAQHLAYPVPDV SEQ ID NO: 434 PGLKVAQHLAYPVPDVP SEQ ID NO: 435 LGFQPGLKVAQHLAYPV SEQ ID NO: 436 ELGFQPGLKVAQHLAYP SEQ ID NO: 437 ELGFQPGLKVAQHLAYPV SEQ ID NO: 438 QPGLKVAQHLAYPVPDVP SEQ ID NO: 439 LGFQPGLKVAQHLAYPVP SEQ ID NO: 440 FQPGLKVAQHLAYPVPDV SEQ ID NO: 441 GFQPGLKVAQHLAYPVPD SEQ ID NO: 442 FQPGLKVAQHLAYPVPDVP SEQ ID NO: 443 LGFQPGLKVAQHLAYPVPD SEQ ID NO: 444 GFQPGLKVAQHLAYPVPDV SEQ ID NO: 445 ELGFQPGLKVAQHLAYPVP SEQ ID NO: 446 LGFQPGLKVAQHLAYPVPDV SEQ ID NO: 447 ELGFQPGLKVAQHLAYPVPD SEQ ID NO: 448 GFQPGLKVAQHLAYPVPDVP SEQ ID NO: 449 ELGFQPGLKVAQHLAYPVPDV SEQ ID NO: 450 LGFQPGLKVAQHLAYPVPDVP SEQ ID NO: 451

The peptides that mimic the helices and functional fragments thereof are administered in formulations and by routes well understood. A variety of methods for introducing such substances are known, typically, by injection, aerosol administration, suppository, and, with proper design, oral administration. This general statement is true as well with respect to providing expression systems for peptides represented by the helix mimics.

In addition to the peptides or other compounds of the invention, combination therapies including known HCV inhibitors can be utilized in the present invention. For example, it may be desirable to administer both a peptide or peptides of the invention in combination with interferon to a subject infected with HCV. Other drugs or compounds known in the art to be effective against HCV, can also be used.

In one embodiment, the invention provides a method of screening compounds, to identify those that selectively inhibit the binding of HCV nonstructural proteins (for example, NS4B or NS5A) and cellular membranes. Methods known to those of skill in the art, can be readily adapted to detect interference with the binding of these components. The method of screening may involve high-throughput techniques. For example, to screen for compounds that selectively inhibit the binding of HCV nonstructural proteins and cellular membranes, a synthetic reaction mix, a viral fragment or component, or a preparation of any thereof, comprising an HCV nonstructural protein and a labeled substrate or ligand of such polypeptide is incubated in the absence or the presence of a candidate molecule that may inhibit the binding of the HCV nonstructural proteins and the cellular membrane. The ability of the candidate molecule to inhibit the binding of the HCV nonstructural protein and the cellular membrane is reflected in decreased binding of the labeled ligand or decreased production of product from such substrate.

In another aspect, the screening can be performed by adding the candidate compound to intact cells that have been infected by HCV, or that contain an HCV replicon, and then examining the component of interest to demonstrate the effect on this component, or the effect on viral or replicon replication. An exemplary cell-based in vitro assay for this purpose is disclosed in PCT International Publication WO 02/18369. Alternatively, the screening can be performed by adding the test agent to in vitro translation reactions and then proceeding with the established analysis. As another alternative, purified or partially purified components which have been determined to interact with one another by the methods described above can be placed under conditions in which the interaction between them would normally occur, with and without the addition of the candidate compound, and the procedures previously established to analyze the interaction can be used to assess the impact of the candidate compound. However their anti-HCV activity is initially assayed, peptide or other inhibitors of the present invention should cause inhibition of infection, replication, or pathogenesis of Hepatitis C Virus in vitro or in vivo when introduced into a host cell containing the virus, and exhibit an IC₅₀ in the range of from about 0.0001 nM to 100 μM in an in vitro assay for at least one step in infection, replication, or pathogenesis of HCV, more preferably from about 0.0001 nM to 75 μM, more preferably from about 0.0001 nM to 50 μM, more preferably from about 0.0001 nM to 25 μM, more preferably from about 0.0001 nM to 10 μM, and even more preferably from about 0.0001 nM to 1 μM.

In another embodiment of the invention, the method of screening may be by phage display. A method of obtaining selective ligands that bind a chosen target is to select from a library of proteins or peptides displayed on phage. In order to obtain a novel binding protein against a chosen target, such as an amphipathic helix region of an HCV component, DNA molecules, each encoding a protein or peptide fragment thereof, and a structural signal calling for the display of the protein on the outer surface of a chosen genetic package (bacterial cell, bacterial spore or phage) are introduced into a genetic package. The protein is expressed and the potential binding domain is displayed on the outer surface of the package. The package is then exposed to the target. If the genetic package binds to the target, then it is confirmed that the corresponding binding domain is indeed displayed by the genetic package. Packages which display the binding domain (and thereby bind the target) are separated from those which do not. For example, in the present invention, the target may be the amphipathic helix or a mutated amphipathic helix. Potential peptides, which may then be used as anti-HCV agents, are screened by determination of which will bind to the amphipathic helix or a mutated amphipathic helix. Preferred peptides are those that not only bind to the amphipathic helix, but in addition, block or inhibit the amphipathic helix from binding to its receptor or binding site, thereby inhibiting infectivity. Examples of peptides identified by phage display are set forth in Table 3.

TABLE 3 Peptides identified by phage display as ligands of the amphipathic helix of NS5A: Sequence Identification Sequence Number HDSFANATGRFWP SEQ ID NO: 454 QGTSPSRLAVPLA SEQ ID NO: 455 ISSKTGMSSEPPS SEQ ID NO: 456 ILSSIDALGSDSH SEQ ID NO: 457 LDDRSVPTVISQR SEQ ID NO: 458 YPSKPGNVTPKAP SEQ ID NO: 459 QAQGERALK SEQ ID NO: 460 TDKRASPLTVQAR SEQ ID NO: 461

In all of the embodiments of the invention, the active agent which will interact, generally, either with the sites on the cytoplasmic membrane to which the amphipathic helix binds or will interact with the amphipathic helix itself, may be derivatized or coupled to additional components. By “derivatives” of these agents is meant modifications thereof that do not interfere with their ability to interact with the sites or the helix, but may optionally confer some additional useful property. One particularly useful property is the ability to penetrate cell membranes, and preferred among the derivatives or conjugated forms are those coupled to such facilitators. An additional desired coupled component may be a labeling component such as a fluorescent dye, an enzyme, or a radioisotope. One particularly useful label is, for example, green fluorescent protein in any of its many colors and forms. Green fluorescent protein thus, includes, not only forms of this fluorescent protein that fluoresce green, but also those that fluoresce various other colors such as red and blue. These forms of the protein are commercially available as are recombinant materials for their production.

The compositions of the invention can be administered as conventional HCV therapeutics. The compositions of the invention may include more than one ingredient which interrupts the binding of the amphipathic helix to the membranes and more than one peptide of the invention.

The precise formulations and modes of administration of the anti-HCV compositions of the invention will depend on the nature of the anti-HCV agent, the condition of the subject, and the judgment of the practitioner. Design of such administration and formulation is routine optimization generally carried out without difficulty by the practitioner.

In addition to the assay methods, methods to identify compounds or protocols against HCV infection, and methods to treat HCV infections as set forth above, the invention provides compositions which are effective to elicit immunological responses to HCV in appropriate subjects, such as humans or other animals subject to HCV infection.

Administration may be performed using conventional methods, typically by injection. The elicited immunological response is helpful in general HCV prophylaxis.

The following examples are intended to illustrate but not to limit the invention.

EXAMPLES Example 1 Effect of Helix Disruption on Membrane Association

The bottom panels of FIGS. 3A-3C show the structures of the relevant portion of NS5A used in this example. FIG. 3A shows the amino acid sequence and helix formed at positions 4-27 in the NS5A protein of Hepatitis C virus genotype 1a. FIG. 3B shows the deletion of positions 7-27, thus deleting the helix, as shown by the brackets. This deletion was conducted by PCR mutagenesis essentially as described by Glenn, J. S., et al., J. Virol (1998) 72:9303-9306 on plasmid pBRTM/HCV 827-3011 which encodes the HCV nonstructural proteins as described by Grakoui, A., et al., J. Virol. (1993) 67:1385-1395. This vector encodes the NS proteins under the T7 promoter and encephalomyocarditis internal ribosome entry site control elements and directs the synthesis and processing of proteins NS3, NS4A, NS4B, NS5A and NS5B. FIG. 3C shows a mutant which was obtained using PCR mutagenesis as described above using a primer

(SEQ ID NO: 452) (5′-TCCGGCTCCTGGCTAAGGGAC GA CTGGGACTGG GA ATGCGAGGTGC T-GAGCGAC GA TAAGACC-3′) in which codons isoleucine-8, isoleucine-12, and phenylalanine-19 of NS5A were changed to encode aspartate, glutamate, and aspartate, respectively. This results in disruption of the hydrophobic region of the helix.

Each of these plasmids was expressed and distribution of the NS5A protein, which is produced by the plasmids in cells, was observed. A liver derived cell line, Huh-7, was first infected with recombinant vaccinia virus encoding T7-RNA polymerase and then transfected with pBRTM/HCV 827-3001, or by this plasmid modified as described in FIGS. 3B and 3C.

After incubation to effect protein production, the cells were fixed with formaldehyde and immunostained with a monoclonal antibody against NS5A and a Texas Red-labeled donkey anti-mouse secondary antibody essentially as described by Glenn, J. S., et al., J. Virol. (1990) 64:3104-3107. As shown in the upper panel of FIG. 3A, perinuclear punctuate vesicular staining suggestive of a Golgi-like intracellular distribution pattern was readily observed, as was, occasionally, a somewhat reticulin chicken-wire-like staining pattern, characteristic of the ER. Both patterns have been reported previously when NS5A is expressed either alone or in combination with other HCV NS proteins using a variety of expression systems. See, for example, Kim, J. E., et al., Arch. Virol. (1999) 144:329-343; Huang, Y., et al., Biochem. Biophys. Res. Commun. (2001) 281:732-740.

However, when the construct of FIG. 3B, containing a deleted portion of NS5A was expressed, as shown in the upper panel of FIG. 3B, cytoplasmic membrane localization was abolished and a nuclear localization pattern was obtained. A cryptic nuclear localization signal in the NS5A C-terminal domain has previously been reported by Ide, Y., et al., Gene (1996) 182:203-211.

When the construct described in FIG. 3C, which disrupts the hydrophobic face of the helix, is expressed in these cells, again, as shown in the upper panel of FIG. 3C, the cytoplasmic membrane localization pattern was lost and localization to the nucleus was observed.

FIGS. 3A-3C show these results at two magnification levels. The uppermost panel in each case shows results for a single cell and the intermediate panel shows results for a number of cells. As shown in the intermediate panels in FIGS. 3B and 3C, occasionally distribution of the dye throughout the cell was observed rather than localization to the nucleus. However, even in these cases, no specific localization to the cytoplasmic membrane could be detected.

Example 2 Intracellular Location of GFP-Labeled Helix

Three constructs were made. First, as a control, the HCV encoding sequences of pBRTM/HCV 827-3011 were replaced with the coding sequence for jellyfish Aequorea Victoria green fluorescent protein (GFP) using a PCR cloned insert from plasmid C109 which contains E-GFP (Clontech), to obtain “T7-GFP.” A fragment of the NS5A gene encoding the amphipathic helix was fused into frame with the sequence encoding the N-terminus of GFP in T7-GFP by creating a common PstI site using PCR mutagenesis. This permits junction of the first 31 amino acids of NS5A to the 5′ side of serine-2 of the GFP-encoding sequence in T7-GFP. The resulting vector was labeled “T7-5AGFP.” A similar vector, designated “T7-5ANHGFP” was constructed in a manner similar to “T7-5AGFP” except that the corresponding segment from the mutated form of NS5A set forth in FIG. 3C was employed in place of the wildtype helix. Thus, “T7-5ANHGFP” is similar to “T7-5AGFP” except that in the NS5A helix, Ile at position 8 is converted to Asp, Ile at position 12 is converted to Glu, and Phe at position 19 is converted to Asp.

These constructs were used to effect expression of GFP or of the GFP fusions in Huh-7 cells as described in Example 1 and the distribution of fluorescence was evaluated with the results as shown in FIGS. 4A-4C. As shown in FIG. 4A, cells expressing GFP alone show a wide diffuse pattern including concentration in the nucleus. Cells expressing 5AGFP show distribution of fluorescence similar to that of the NS5A protein itself with a Golgi-like intracellular distribution pattern and ER staining. Cells expressing 5ANHGFP failed to show this pattern but instead mimic the distribution pattern of GFP.

Example 3 Effect of Helix Disruption on HCV RNA Replication

Comparative high efficiency, second generation, bicistronic, subgenomic RNA replicons of HCV described by Blight, K. J., et al., Science (2001) 290:1972-1974 were constructed with a neomycin-resistance gene. Similar constructs were made with wildtype NS5A and with NS5A altered in the amphipathic helix as described in Examples 1 and 2. Diagrams of these constructs are shown in the upper panels of FIGS. 5A and 5B.

The construct containing the wildtype NS5A, Bart79I, was made by PCR mutagenesis of HCVrep1bBartMan/AvaII (Blight, supra) such that nucleotide 5336 was changed from a G to T resulting in a change in NS5A codon 1179 from serine to isoleucine. This mutation results in a dramatic increase in replication efficiency of the HCV subgenomic replicon. Bart5X79I (containing the modified helix) was made by PCR mutagenesis of Bart79I using a primer

(SEQ ID NO: 453) (5′-G A TTGGGATTGG GA ATGCACGGTGTTGACTGAT GA CAAGACC TGG-3′) in which codons valine-8, isoleucine-12, and phenylalanine-19 of NS5A were changed to encode aspartate, glutamate, and aspartate, respectively. All mutations were confirmed by DNA sequencing.

The RNA replication efficiency was then assayed by ability to establish G418-resistant colonies after transfection of Huh-7 cells as follows: Replicon RNA's were prepared by in vitro transcription with T7-RNA polymerase of ScaMinearized plasmids (Bart79I or Bart5X79I) followed by DNase treatment and purification. Replicons were then electroporated into Huh-7 cells and neomycin-resistant colonies selected by inclusion of 1 mg/ml G418 in the culture media. Methods were essentially as described by Blight (supra). Colonies were detected by staining with cresyl violet. Multiple independent preparations of replicons and replication assays yielded similar results.

As shown in FIG. 5A, lower panel, the replicon with wildtype NS5A N-terminus gave rise to numerous colonies while disrupting the amphipathic nature of the N-terminal helix results in a dramatic inhibition of HCV genome replication as shown in the lower panel of FIG. 5B.

There was no decreased transfection efficiency or any decrease in the ability to establish colonies when control experiments using plasmids encoding drug resistance marker along with only the wildtype or mutant NS5A proteins were used in place of the replicons above, thus establishing that the results were not due to an increased cytotoxicity associated with mutant NS5A.

Example 4 Floatation Assay

In this membrane floatation assay, the ability of the NS5A amphipathic helix to bind to a preparation of microsomal membranes was tested. NS5A proteins, both the NS5A wildtype or mutant amphipathic helix (described in Example 1), were in vitro translated and [³⁵S]-labeled using the Promega TNT reticulocyte lysate kit. Plasmids pC5A or pC5ANH were used as transcription templates. Aliquots of the reactions were combined with a membrane fraction derived from Huh-7 cells, with or without synthetic peptides, and overlayed with a 5-40% OptiPrep step gradient. After centrifugation for 4 hrs at 40,000×g in a SW60 rotor, 500 ml fractions were collected from the top and the proteins in each gradient fraction were precipitated and analyzed by SDS-PAGE. The percentage of protein “floating” to the top of the gradient with membranes (fraction 2 from the top) was then quantified using a Molecular Dynamics phosphorimager.

FIGS. 6A and 6B show a comparison of the results for wildtype and mutant forms. The numbers correspond to Optiprep gradient (5-40%) fraction number. Non-membrane associated proteins remain at the bottom (right side) of the gradient, whereas membranes—and associated proteins—“float” towards less dense gradient fractions present at the top (left side). As shown, in the reaction mixture containing wildtype, the synthesized NS5A floated toward the top of the gradient coupled with the membrane. This was not found in the case of the mutant form. In both cases, there was a degree of non-specific binding associated with fractions that settle to the bottom of the gradient. An advantage of this method is elimination of the artifacts caused by non-specific binding, as illustrated by the labeling of high density fractions in both mixtures.

FIG. 6C shows the percentage of NS5A wildtype or mutant protein that float with the membrane fractions as a percentage of the total synthesized. As seen, 25% of the wildtype, but only 0.8% of the mutant, was associated with the membrane.

FIGS. 7A and 7B show the results of a similar floatation experiment in the presence and absence of a test peptide that is a competitive inhibitor of the NS5A helix. This peptide contains amino acids 1-27 of NS5A with a C-terminal “flag” DYKD. The assay described in the preceding paragraph was repeated in the presence and absence of this peptide. As shown in FIG. 7A, the percentage of NS5A floated in the absence of peptide is arbitrarily normalized to 100%; in comparison with this, the presence of the test peptide lowered the percentage to about 21%.

Similarly, the assay was modified by using, in place of NS5A, a fusion protein consisting of the amphipathic helix of NS5A with green fluorescent protein. As can be seen in FIG. 7B, the amount of labeled NS5A floated with the membrane was set in the absence of test peptide at 100%. In comparison, the presence of the test peptide lowered the percentage floated to about 21%.

Moreover, as shown in FIG. 6C, a synthetic peptide designed to mimic the wild type AH not only competitively inhibited membrane association of NS5A, but did so in a dose-dependent manner. The maximal extent of inhibition achieved pharmacologically was comparable to that obtained by genetic mutation of the AH. In addition, the synthetic peptide appears equally effective against NS5A derived from different genotypes (data not shown), including those most refractory to current therapies. This convenient membrane floatation assay has also proven well-suited for current efforts focused on studying the mechanistic details of the AH membrane-targeting domain, and ideal for guiding ongoing development of peptidomimetic compounds designed to resemble key elements, or bind to specific features, of the AH. Such compounds represent an exciting potential addition to current anti-HCV combination therapy regimens.

FIG. 8 shows Pharmacologic inhibition of NS5A membrane association. Huh-7 cells-derived membranes were treated with PEP1 (a peptide mimicking the wild type amphipathic helix of NS5A), PEP2 (a control peptide) or mock-treated with water. PEP1 (a peptide that corresponds to the wild type N-terminal amphipathic helix of NS5A (amino acids 1-26) with a C-terminal FLAG tag) and PEP2 (which is identical to PEP1 except amino acids isoleucine-8, isoleucine-12, and phenylalanine-19 of NS5A were changed to aspartate, glutamate, and aspartate, respectively) were synthesized by AnaSpec Inc. In-vitro translated NS5A (or NS5ANH) was incubated with membranes and various concentrations of peptides or water prior to analysis by membrane floatation assays set forth above. The amount of NS5A floating with no peptide treatment typically is ˜30% of the total in-vitro translated NS5A. For comparison between treatment conditions, results were normalized to the no-treatment control. The percent of NS5A (or NS5ANH) floating with the membranes under the indicated conditions was determined as in FIG. 6A and expressed relative to mock-treated control. Error bars represent standard error of the mean.

While the invention has been described in detail with reference to certain preferred embodiments thereof, it will be understood that modifications and variations are within the spirit and scope of that which is described and claimed.

REFERENCES

-   1. Araga S, Blalock J E. Use of complementary peptides and their     antibodies in B-cell-mediated autoimmune disease: prevention of     experimental autoimmune myasthenia gravis with a peptide vaccine.     Immunomethods. 1994 October; 5(2):130-5. -   2. Araga S, Galin F S, Kishimoto M, Adachi A, Blalock J B.     Prevention of experimental autoimmune myasthenia gravis by a     monoclonal antibody to a complementary peptide for the main     immunogenic region of the acetylcholine receptors. J. Immunol. 1996     Jul. 1; 157(1):386-92. -   3. Araga S, LeBoeuf R D, Blalock J E. Prevention of experimental     autoimmune myasthenia gravis by manipulation of the immune network     with a complementary peptide for the acetylcholine receptor. Proc     Natl Acad Sci USA. 1993 Sep. 15; 90(18):8747-51. -   4. Blalock J E, Bost K L. Binding of peptides that are specified by     complementary RNAs. Biochem J. 1986 Mar. 15; 234(3):679-83. -   5. Blalock J E, Whitaker J N, Benveniste E N, Bost K L. Use of     peptides encoded by complementary RNA for generating anti-idiotypic     antibodies of predefined specificity. Methods Enzymol. 1989;     178:63-74. -   6. Bost K L, Blalock J E. Complementary peptides as interactive     sites for protein binding. Viral Immunol. 1989 Winter; 2(4):229-38. -   7. Bost K L, Blalock J E. Preparation and use of complementary     peptides. Methods Enzymol. 1989; 168:16-28. -   8. Bost K L, Blalock J E. Production of anti-idiotypic antibodies by     immunization with a pair of complementary peptides. J Mol. Recognit.     1989 April; 1(4):179-83. -   9. Bost K L, Smith E M, Blalock J E. Similarity between the     corticotropin (ACTH) receptor and a peptide encoded by an RNA that     is complementary to ACTH mRNA. Proc Natl Acad Sci USA. 1985 March;     82(5):1372-5. -   10. Hawiger, J., Noninvasive intracellular delivery of functional     peptides and proteins. Current Opinion in Chemical Biology, 1999.     3: p. 89-94. -   11. Holsworth D D, Kiely J S, Root-Bernstein R S, Overhiser R W.     Antisense-designed peptides: a comparative study focusing on     possible complements to angiotensin II. Pept Res. 1994 July-August;     7(4):185-93. -   12. Kolykhalov, A. A. and Rice, C. M. (Science 277 (5325), 570-574     (1997). -   13. Maria Lindgren, M. H., Alain Prochiantz, and Ulo Langel,     Cell-penetrating peptides. Trends in Pharmacological Sciences, 2000.     21: p. 99-103. -   14. May C. Morris, J. D., Jean Mery, Frederic Heitz and Gilles     Divita, A peptide carrier for the delivery of biologically active     proteins into mammalian cells. Nature Biotechnology, 2001. 19: p.     1173-1176. -   15. Pfister R R, Haddox J L, Blalock J E, Sommers C I, Coplan L,     Villain M. Synthetic complementary peptides inhibit a neutrophil     chemoattractant found in the alkali-injured cornea. Cornea. 2000     May; 19(3):384-9. -   16. Mauricio Rojas, J. P. D., Zhongjia Tan, and Yao-Zhong Lin,     Genetic engineering of proteins with cell membrane permeability.     Nature Biotechnology, 1998. 16: p. 370-375. -   17. Anne Scheller, B. W., Matthias Meizig, Michael Bienert, and     Johannes Oehlke, Evidence for an amphipathicity independent cellular     uptake of amphipathic cell-penetrating peptides. European Journal of     Biochemistry, 2000. 267: p. 6043-6049. -   18. Swords B H, Can D J, Blalock J E, Berecek K H. An antibody     directed against a peptide encoded by RNA complementary to mRNA for     vasopressin recognizes putative vasopressin receptors.     Neuroendocrinology. 1990 April; 51(4):487-92. -   19. Weigent D A, Clarke B L, Blalock J E. Peptide design using a     genetically patterned binary code: growth hormone-releasing hormone     as a model. Immunomethods. 1994 October; 5(2):91-7. -   20. Xue Yan Liu, D. R., Ruth Ann Veach, Danya Liu, Sheila Timmons,     Robert D. Collins, and Jacek Hawiger, Peptide-directed suppression     of a pro-inflammatory cytokine response. The Journal of Biological     Chemistry, 2000. 275: p. 16774-16778. -   21. Yunfeng Zhao, D. L., John Burkett, Heinz Kohler, Chemical     engineering of cell penetrating antibodies. Journal of Immunological     Methods, 2001. 254: p. 137-145. -   22. Lianshan Zhang, T. R. T., Xue-Yan Liu, Sheila Timmons, Ann D.     Colosia, Jacek Hawiger and James P. Tam, Preparation of functionally     active cell-permeable peptides by single-step ligation of two     peptide modules. Proc. Natl. Acad. Sci. USA, 1998. 95: p. 9184-9189. -   23. Badkar, A., Talluri, K., Tenjarla, S., Jaynes, J., Banga, A., In     Vitro Release Testing of a Peptide Gel. Pharm. Technol., 44-52     (January 2000). -   24. Bernkop-Schnurch, A. Chitosan and its derivatives: potential     excipients for peroral peptide delivery systems. Int. J. Pharm. 194,     1-13 (2000). -   25. Gonda, I., The Ascent of Pulmonary Drug Delivery. J. Pharm. Sci.     89, 940-945 (2000). -   26. Jung, T. Kamm, W., Breitenbach, A., Kaiserling, E., Xiao, J. X.,     Kissel, T., Biodegradable nanoparticles for oral delivery of     peptides: is there a role for polymers to affect mucosal uptake?     Eur. J. Pharm. Biopharm. 50, 147-160 (2000). -   27. Latham, P., Therapeutic Peptides Revisited. Nat. Biotech. 17,     755-757 (1999). -   28. Pillai, O., Nair, V., Poduri, R., Pancchagnula, R., Transdermal     Iontophoresis. Part II: Peptide and Protein Delivery. Methods Find.     Exp. Clin. Pharmacol. 21(3): 229-240 (1999). -   29. Sakuma, S. Hayashi, M., Akashi, M., Design of nanoparticles     composed of graft copolymers for oral peptide delivery. Advanced     Drug Delivery Reviews 47, 21-37 (2001). -   30. Takeuchi, H., Yamamoto, H., Kawashima, Y. Mucoadhesive     nanoparticulate system for peptide drug delivery. Advanced Drug     Delivery Reviews 47, 39-51 (2001). -   31. Veronese, F. M., Morpugo, M., Bioconjugation in pharmaceutical     chemistry. Il Farmaco 54, 497-516 (1999). -   32. Veuillex, F., Kalia, Y. N., Jacques, Y., Dashusses, J., Buri,     P., Factors and strategies for improving buccal absorption of     peptides. Eur. J. Pharm. Biopharm. 51, 93-109 (2001). -   33. Wang, W., Jiang, J., Ballard, C. E., Wang, B., Prodrug     Approaches to the Improved Delivery of Peptide Drugs. Cur. Pharm.     Des. 5, 265-287 (1999). 

What is claimed is:
 1. An isolated peptide of from about 10 to 29 amino acid residues, which comprises an amino acid sequence of an amphipathic helix present in a Hepatitis C Virus (HCV) nonstructural protein, wherein the HCV nonstructural protein is NS4B, and wherein the peptide is not coupled to a heterologous HCV peptide, wherein the peptide comprises an amino acid sequence selected from: (SEQ ID NO: 1) IEQGMMLAEQFKQKALGLLQTASRHAEV; (SEQ ID NO: 18) YIEQGMMLAEQFKQKALGLLQTASRHAE; and (SEQ ID NO: 462) YIEQGMMLAEQFKQKALGLLQTASRHAEV.


2. The isolated peptide of claim 1, which is coupled to a detectable label.
 3. The isolated peptide of claim 2, wherein the detectable label is a fluorescent label or a radioisotope.
 4. The isolated peptide of claim 1, which is coupled to a membrane-penetrating facilitator.
 5. The isolated peptide of claim 1, wherein the peptide comprises a non-peptide isosteric linkage.
 6. The isolated peptide of claim 1, wherein the peptide comprises a non-natural amino acid.
 7. The isolated peptide of claim 6, wherein the non-natural amino acid is a D-amino acid.
 8. The isolated peptide of claim 1, wherein the peptide is bound to a solid support.
 9. The isolated peptide of claim 1, wherein the peptide is 26-29 amino acid residues in length.
 10. The isolated peptide of claim 1, wherein the peptide comprises the amino acid sequence (SEQ ID NO: 1) IEQGMMLAEQFKQKALGLLQTASRHAEV.


11. The isolated peptide of claim 1, wherein the peptide comprises the amino acid sequence (SEQ ID NO: 18) YIEQGMMLAEQFKQKALGLLQTASRHAE.


12. The isolated peptide of claim 1, wherein the peptide comprises the amino acid sequence (SEQ ID NO: 462) YIEQGMMLAEQFKQKALGLLQTASRHAEV.


13. A composition comprising: a) the isolated peptide of claim 1; and b) a pharmaceutically acceptable carrier, diluent, excipient, or buffer suitable for administering to a human.
 14. The composition of claim 13, wherein the composition is formulated for administration by injection.
 15. The composition of claim 13, wherein the composition is formulated for oral administration. 